Destroyed topic simple machines. Methodical development of classes in English on the theme "Machines and work" (3 year)

HanicalSimple Machines   and its Mechanical Advantage What are Simple Machines ? What do we mean by Mechanical Advantage? Simple Machines    * creates a greater output force than the input force Therefore since work is performed by applying a force over a distance, with the use of these machines   we can do more work with lesser effort than working with our bare hands. In short, they make work easier. Mechanical Advantage * The Ratio between the input force and the output force. * The measure of the force amplification achieved by using a tool, mechanical device or machine   system. Anyway what is input and output force? Input refers to the force you applied while output refers to the resultant force the object has from the input force. Example: I pushed a ball with 10 N of force, it is rolling with 10 N of force. I input 10 N into it, now it is outputting 10 N. The Six Classical Simple Machines   The Lever (French word that means “to raise”) * A simple machine   that allows you to gain a mechanical advantage in moving an object or in applying a force to an object. It is considered a "pure" simple machine   because friction is not a factor to overcome, as in other simple machines . Part | Description | Fulcrum | Is where a solid board or rod can pivot ...

Simple Machines Examples With Pictures Essay

Applied Force Other First Class Lever Examples Applied Force Action Force Spring Load Force Action http://library.thinkquest.org/J002079F/lever.htm Third Class Lever Effort or Applied Force Egg ready to be launched Release hook Compressed Spring Load or Resistance Fulcrum Applied force can be in any direction http://www.usoe.k12.ut.us/curr/science/sciber00/8th/ machines /sciber/lever3.htm http://www.usoe.k12.ut.us/curr/science/sciber00/8th/ machines /images/tweezer.gif http://www.usoe.k12.ut.us/curr/science/sciber00/8th/ machines /images/base.jpg Inclined Plane An inclined plane is a slanted surface used to raise an object. An inclined plane decreases the size of the effort force needed to move an object. However, the distance through which the effort force is applied is increased. The Big Rock rolling downhill with gravitational force IS NOT an example of an inclined plane. The inclined plane gives you mechanical advantage AGAINST gravity. Big Rock http://www.sirinet.net/~jgjohnso/simple.html An example of how an Inclined Plane can be used to raise a mass to activate another simple machine   Egg ready to be launched By First Class Lever F Big Rock Force pushing (or pulling) Big Rock up the hill Inclined Plane First Class Lever Wedges Pulleys Wedges are moving inclined planes that are driven under loads to lift Pulleys use a wheel or set of wheels around which a single length (not ...

Activity 1.1.2 Simple Machines Practice Problems Answer Key Essay

Activity 1.1.2 Simple Machines   Practice Problems Answer Key Procedure Answer the following questions regarding simple machine   systems. Each question requires proper illustration and annotation, including labeling of forces, distances, direction, and unknown values. Illustrations should consist of basic simple machine   functional sketches rather than realistic pictorials. Be sure to document all solution steps and proper units. All problem calculations should assume ideal conditions and no friction loss. Simple Machines   - Lever A first class lever in static equilibrium has a 50lb resistance force and 15lb effort force. The lever’s effort force is located 4 ft from the fulcrum. 1. Sketch and annotate the lever system described above. 2. What is the actual mechanical advantage of the system? Formula Substitute / Solve Final Answer AMA \u003d 3.33 3. Using static equilibrium calculations, calculate the length from the fulcrum to the resistance force. Formula Substitute / Solve Final Answer A wheel barrow is used to lift a 200 lb load. The length from the wheel axle to the center of the load is 2 ft. The length from the wheel and axle to the effort is 5 ft. 4. Illustrate and annotate the lever system described above. 5. What is the ideal mechanical advantage of the system? ...

Compound machine

Our compound machine , consisting of mainly three different simple machines , is a crane designed to multiply your force in order to effectively and efficiently lift the four 75 kg up a steep hill. Our machine starts off with the gear train. As you rotate the handle, all the gears rotate along as well. Since we connected the rope of the pulley to our gears, it then puts the pulley system into action. We created movable pulleys throughout the arm until the tip to stabilize our rope and also give us a mechanical advantage. At the top section of our arm we created a lever to support the load. This magnifies our effort force since a combination of all the mechanical energy is being carried out. With the pulley system, connected all the way to the gear train, and the lever working all together, our mechanical advantage is increased greatly. We created a series of gear trains to not only increase our advantage of torque in the machine   but also to increase the mechanical advantage rather than losing efficiency due to friction and thermal energy. Doing this, we magnified our effort force onto the load. Also, in the gears, we arranged it so that the input gear and the output gear gave us a low gear ratio and the idler gears in between. It also allows us to control the direction of our force in the machine . Since it is linked to the pulley, we can control the direction of the rope. However, it only ...

Essay

SAMPLE PROBLEMS:. Simple Machines - Lever A first class lever in static equilibrium has a 50lb resistance force and 15lb effort force. The lever’s effort force is located 4 ft from the fulcrum. Sketch and annotate the lever system described above. | What is the actual mechanical advantage of the system? Formula | Substitute / Solve | Final Answer | | | AMA \u003d 3.33 | * Using static equilibrium calculations, calculate the length from the fulcrum to the resistance force. Formula | Substitute / Solve | Final Answer | | | | A wheel barrow is used to lift a 200 lb load. The length from the wheel axle to the center of the load is 2 ft. The length from the wheel and axle to the effort is 5 ft. Illustrate and annotate the lever system described above. | What is the ideal mechanical advantage of the system? Formula | Substitute / Solve | Final Answer | | | | * Using static equilibrium calculations, calculate the effort force needed to overcome the resistance force in the system. Formula | Substitute / Solve | Final Answer | | | | A medical technician uses a pair of four inch long tweezers to remove a wood sliver from a patient. The technician is applying 1 lb of squeezing force to the tweezers. If more than 1/5 lb of force is applied to the sliver, it will break and become difficult to remove. Sketch and annotate the lever system ...

Essay on Simple Machines

...Simple machines   are extremely important to everyday life. They make stuff that is normally difficult a piece of cake. There are several types of simple machines . The first simple machine   is a lever. A lever consists of a fulcrum, load, and effort force. A fulcrum is the support. The placing of the fulcrum changes the amount of force and distance it will take in order to move an object. The load is the applied force. The effort force is the force applied on the opposite side of the load. Levers can be placed in three classes. The 1st class levers are objects like pliers where the fulcrum is at the center of the lever. The 2nd class of levers are objects that have the fulcrum on the opposite side of the applied force like a nutcracker. The 3rd and final class is objects like crab claws. These objects of the load at one end and the fulcrum on the other. An inclined plane is another simple machine . Inclined planes are also known as ramps. Ramps make a trade off between distance and force. No matter how steep the ramp, the work is still the same. A winding road on a mountain side is a good example of a ramp. Some simple machines   are modified inclined planes. The wedge is one of those machines . One or two inclined planes make up a wedge. Saws, knives, needles, and axes are made from wedges ....

Simple machines essay

...Simple Machines   Definitions: Machine - A device that makes work easier by changing the speed, direction, or amount of a force. Simple Machine - A device that performs work with only one movement. Simple machines   include lever, wheel and axle, inclined plane, screw, and wedge. Ideal Mechanical Advantage (IMA) - A machine   in which work in equals work out; such a machine   would be frictionless and a 100% efficient IMA \u003d De / Dr Actual Mechanical Advantage (AMA) - It is pretty much the opposite of IMA meaning it is not 100% efficient and it has friction. AMA \u003d Fr / Fe Efficiency- The amount of work put into a machine   compared to how much useful work is put out by the machine ; always between 0% and 100%. Friction- The force that resist motion between two surfaces that are touching each other. What do we use machines   for? Machines   are used for many things. Machines   are used in everyday life just to make things easier. You use many machines   in a day that you might take for granted. For example a simple   ordinary broom is a machine . It is a form of a lever. Our country or world would never be this evolved if it wasn "t for machine . Almost every thing we do has a machine   involved. We use machines ...

Simple Machine A machine with few Essay

... Simple Machine : A machine   with few or no moving parts. Simple machines   make work easier. Examples: Screw, Wheel and Axle, Wedge, Pulley, Inclined Plane, Lever Compound Machine : Two or more simple machines working together to make work easier. Examples: Wheelbarrow, Can Opener, Bicycle Inclined plane: A sloping surface, such as a ramp. Makes lifting heavy loads easier. The trade-off is that an object must be moved a longer distance than if it was lifted straight up, but less force is needed. Examples: Staircase, Ramp Lever: A straight rod or board that pivots on a point known as a fulcrum. Pushing down on one end of a lever results in the upward motion of the opposite end of the fulcrum. Examples: Door on Hinges, Seesaw, Hammer, Bottle Opener Pulley: A wheel that usually has a groove around the outside edge for a rope or belt. Pulling down on the rope can lift an object attached to the rope. Work is made easier because pulling down on the rope is made easier due to gravity. Examples: Flag Pole, Crane, Mini-Blinds Screw: An inclined plane wrapped around a shaft or cylinder. This inclined plane allows the screw to move itself or to move an object or material surrounding it when rotated. Examples: Bolt, Spiral Staircase Wedge: Two inclined planes joined back to back. Wedges are used to split things ....

  Simple machines are devices with few or no moving parts that make work easier. Students are introduced to the six types of simple machines - the wedge, wheel and axle, lever, inclined plane, screw, and pulley - in the context of the construction of a pyramid, gaining high-level insights into tools that have been used since ancient times and are still in use today. In two hands-on activities, students begin their own pyramid design by performing materials calculations, and evaluating and selecting a construction site. The six simple machines are examined in more depth in subsequent lessons in this unit. This engineering curriculum meets Next Generation Science Standards (NGSS).

Engineering connection

Why do engineers care about simple machines? How do such devices help engineers improve society? Simple machines are important and common in our world today in the form of everyday devices (crowbars, wheelbarrows, highway ramps, etc.) that individuals, and especially engineers, use on a daily basis. The same physical principles and mechanical advantages of simple machines used by ancient engineers to build pyramids are employed by today "s engineers to construct modern structures such as houses, bridges and skyscrapers. Simple machines give engineers added tools for solving everyday challenges.

Learning objects

After this lesson, students should be able to:

• Understand what a simple machine is and how it would help an engineer to build something.
• Identify six types of simple machines.
• Understand how the same physical principles used by engineers today to build skyscrapers were employed in ancient times by engineers to build pyramids.
• Generate and compare multiple possible solutions to creating a simple lever machine based on how well each met the constraints of the challenge.

More Curriculum Like This

Levers that lift

Students are introduced to three of the six simple machines used by many engineers: lever, pulley, and wheel-and-axle. In general, engineers use the lever to magnify the force applied to an object, the pulley to lift heavy loads over a vertical path, and the wheel-and-axle to magnify the torque appl ...

Slide Right on by Using an Inclined Plane

Students explore building a pyramid, learning about the simple machine called an inclined plane. They also learn about another simple machine, the screw, and how it is used as a lifting or fastening device.

Splash, Pop, Fizz: Rube Goldberg Machines

Refreshed with an understanding of the six simple machines; screw, wedge, pully, incline plane, wheel and axle, and lever, student groups receive materials and an allotted amount of time to act as mechanical engineers to design and create machines that can complete specified tasks.

Pyramid Building: How to Use a Wedge

Students learn how simple machines, including wedges, were used in building both ancient pyramids and present-day skyscrapers. In a hands-on activity, students test a variety of wedges on different materials (wax, soap, clay, foam).

Educational standards

Each Teachengineering   lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in Teachengineering   are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2l   (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

  NGSS: Next Generation Science Standards - Science

  International Technology and Engineering Educators Association - Technology

Introduction / Motivation

How did the Egyptians build the Great Pyramids thousands of years ago (~ 2,500 BCE)? Could you build a pyramid using 9,000-kilogram (~ 10-ton or 20,000-lb) blocks of stone with your bare hands? That "s like trying to move a large elephant with your bare hands! How many people might it take to move a block that big? It would still be a challenge to build a pyramid today even with modern tools, such as jackhammers, cranes, trucks and bulldozers. But without these modern tools, how did Egyptian workers cut, shape, transport and place enormous stones? Well, one key to accomplishing this amazing and difficult task was the use of simple machines.

  Simple machines   are devices with no, or very few, moving parts that make work easier. Many of today’s complex tools are really just more complicated forms of the six simple machines. By using simple machines, ordinary people can split huge rocks, hoist large stones, and move blocks over great distances.

However, it took more than just simple machines to build the pyramids. It also took tremendous planning and a great design. Planning, designing, working as a team and using tools to create something, or to get a job done, is what engineeringis all about. Engineers use their knowledge, creativity and problem-solving skills to accomplish some amazing feats to solve real-world challenges. People call on engineers to use their understanding of how things work to do seemingly impossible jobs and make everyday activities easier. It is surprising how many times   engineersturn to simple machines to solve these problems.

Once we understand simple machines, you will recognize them in many common activities and everyday items. (Hand out.) These are the six simple machines:   wedge, wheel and axle, lever, inclined plane, screw, and   pulley. Now that you see the pictures, do you recognize some of these simple machines? Can you see any of these simple machines around the classroom? How do they work? Well, an important vocabulary term when learning about simple machines is   mechanical advantage. Mechanical advantage of simple machines means we can use less   forceto move an object, but we have to move it a longer distance. A good example is pushing a heavy object up a ramp. It may be easier to push the object up a ramp instead of just lifting it up to the right height, but it takes a longer distance. A ramp is an example of the simple machine called an inclined plane. We are going to learn a lot more about each of these six simple machines that are a simple solution to helping engineers, and all humans, do hard work.

Sometimes it is difficult to recognize simple machines in our lives because they look different than the examples we see at school. To make our study of simple machines easier, let "s imagine that we are living in ancient Egypt and that the leader of the country has hired us as engineers to build a pyramid. Today" s availability of electricity and technologically-advanced machines make it difficult for us to see what the simple machine is accomplishing. But in the context of ancient Egypt, the simple machines that we will study are the much more basic   toolsof the time. After we develop an understanding of simple machines, we will shift our context to building a skyscraper in the present day, so we can compare and contrast how simple machines were used across the centuries and are still used today.

Lesson background and concepts for teachers

Use the attached Introduction to Simple Machines PowerPoint presentation and Simple Machines Reference Sheet as helpful classroom tools. (Show the PowerPoint presentation, or print out the slides to use with an overhead projector. The presentation is animated to promote an inquiry-based style; each click reveals a new point about each machine; have students suggest characteristics and examples before you reveal them .)

Simple machines are everywhere; we use them everyday to perform simple tasks. Simple machines have also been in use since the early days of human existence. While simple machines take many shapes, they come in six basic types:

•   Wedge: A device that forces things apart.
•   Wheel and axle: Used to reduce friction.
•   Lever: Moves around a pivot point to increase or decrease mechanical advantage.
•   Inclined plane: Raises objects by moving up a slope.
•   Screw: A device that can lift or hold things together.
•   Pulley: Changes the direction of a force.

We use simple machines because they make work easier. The scientific definition of workis the amount of   forcethat is applied to an object multiplied by the distance the object is moved. Thus, work consists of force and distance. Each job takes a specific amount of work to finish it, and this number does not change. Thus, the force times the distance always equals the same amount of work. This means that if you move something a smaller distance you need to exert a greater force. On the other hand, if you want to exert less force, you need to move it over a greater distance. This is the force and distance trade off, or   mechanical advantage, which is common to all simple machines. With mechanical advantage, the longer a job takes, the less force you need to use throughout the job. Most of the time, we feel that a task is hard because it requires us to use a lot of force. Therefore, using the trade off between distance and force can make our task much easier to complete.

The wedge is a simple machine that forces objects or substances apart by applying force to a large surface area on the wedge, with that force magnified to a smaller area on the wedge to do the actual work. A nail is a common wedge with a wide nail head area where the force is applied, and a small point area where the concentrated force is exerted. The force is magnified at the point, enabling the nail to pierce wood. As the nail sinks into the wood, the wedge shape at the point of the nail moves forward, and forces the wood apart.

Figure 1: An ax is an example of a wedge.

Everyday examples of wedges include an ax (see Figure 1), nail, doorstop, chisel, saw, jackhammer, zipper, bulldozer, snow plow, horse plow, zipper, airplane wing, knife, fork and bow of a boat or ship.

The wheel and axle is a simple machine that reduces the friction involved in moving an object, making the object easier to transport. When an object is pushed, the force of friction must be overcome to start it moving. Once the object is moving, the force of friction opposes the force exerted on the object. The wheel and axle makes this easier by reducing the friction involved in moving an object. The wheel rotates around an axle (essentially a rod that goes through the wheel, letting the wheel turn), rolling over the surface and minimizing friction. Imagine trying to push a 9,000-kilogram (~ 10-ton) block of stone. Wouldn "t it be easier to roll it along using logs placed underneath the stone?

Everyday examples of the wheel and axle include a car, bicycle, office chair, wheel barrow, shopping cart, hand truck and roller skates.

A lever simple machine consists of a load, a fulcrum and effort (or force). The load is the object that is moved or lifted. The fulcrum is the pivot point, and the effort is the force required to lift or move the load. By exerting a force on one end of the lever (the applied force), a force at the other end of the lever is created. The applied force is either increased or decreased, depending on the distance from the fulcrum (the point or support on which a lever pivots) to the load, and from the fulcrum to the effort.

  Figure 2: A crowbar is an example of a lever.

copyright

Copyright © 2004 Microsoft Corporation, One Microsoft Way, Redmond, WA 98052-6399 USA. All rights reserved. With notations by the ITL Program, University of Colorado at Boulder, 2005.

Everyday examples of levers include a teeter-totter or see-saw, crane arm, crow bar, hammer (using the claw end), fishing pole and bottle opener. Think of a how you use a crowbar (see Figure 2). By pushing down on the long end of the crowbar, a force is created at the load end over a smaller distance, once again, demonstrating the tradeoff between force and distance.

Inclined planes make it easier to lift something. Think of a ramp. Engineers use ramps to easily move objects to a greater height. There are two ways to raise an object: by lifting it straight up, or by pushing it diagonally up. Lifting an object straight up moves it over the shortest distance, but you must exert a greater force. On the other hand, using an inclined plane requires a smaller force, but you must exert it over a longer distance.

Everyday examples of inclined planes include highway access ramps, sidewalk ramps, stairs, inclined conveyor belts, and switchback roads or trails.

  Figure 3: A car jack is an example of a screw-type simple machine that enables one person to lift up the side of a car.

A screw is essentially an inclined plane wrapped around a shaft. Screws have two primary functions: they hold things together, or they lift objects. A screw is good for holding things together because of the threading around the shaft. The threads grip the surrounding material like teeth, resulting in a secure hold; the only way to remove a screw is to unwind it. A car jack is an example of a screw being used to lift something (see Figure 3).

Everyday examples of screws include a screw, bolt, clamp, jar lid, car jack, spinning stool and spiral staircase.

  Figure 4: A pulley on a ship helps people pull in a heavy fishing net.

A pulley is a simple machine used to change the direction of a force. Think of raising a flag or lifting a heavy stone. To lift a stone up into its place on a pyramid, one would have to exert a force that pulls it up. By using a pulley made from a grooved wheel and rope, one can pull   downon the rope, capitalizing on the force of gravity, to lift the stone   up. Even more valuable, a system of several pulleys can be used together to reduce the force needed to lift an object.

Everyday examples of pulleys in use include flag poles, elevators, sails, fishing nets (see Figure 4), clothes lines, cranes, window shades and blinds, and rock climbing gear.

Compound machines

A compound machine is a device that combines two or more simple machines. For example, a wheelbarrow combines the use of a wheel and axle with a lever. Using the six basic simple machines, all sorts of compound machines can be made. There are many simple and compound machines in your home and classroom. Some examples of the compound machines you may find are a can opener (wedge and lever), exercise machines / cranes / tow trucks (levers and pulleys), shovel (lever and wedge), car jack (lever and screw), wheel barrow ( wheel and axle and lever) and bicycle (wheel and axle and pulley).

Vocabulary / definitions

Design:   (verb) To plan out in systematic, often graphic form. To create for a particular purpose or effect. Design a building. (noun) A well thought-out plan.

Engineering:   Applying scientific and mathematical principles to practical ends such as the design, manufacture and operation of efficient and economical structures, machines, processes and systems.

Force:   A push or pull on an object.

Inclined plane:   A simple machine that raises an object to greater height. Usually a straight slanted surface and no moving parts, such as a ramp, sloping road or stairs.

Lever:   A simple machine that increases or decreases the force to lift something. Usually a bar pivoted on a fixed point (fulcrum) to which force is applied to do work.

Mechanical advantage:   An advantage gained by using simple machines to accomplish work with less effort. Making the task easier (which means it requires less force), but may require more time or room to work (more distance, rope, etc.). For example, applying a smaller force over a longer distance to achieve the same effect as applying a large force over a small distance. The ratio of the output force exerted by a machine to the input force applied to it.

Pulley: A simple machine that changes the direction of a force, often to lift a load. Usually consists of a grooved wheel in which a pulled rope or chain runs.

Pyramid:   A massive structure of ancient Egypt and Mesoamerica used for a crypt or tomb. The typical shape is a square or rectangular base at the ground with sides (faces) in the form of four triangles that meet in a point at the top. Mesoamerican temples have stepped sides and a flat top surmounted by chambers.

Screw:   A simple machine that lifts or holds materials together. Often a cylindrical rod incised with a spiral thread.

Simple machine:   A machine with few or no moving parts that is used to make work easier (provides a mechanical advantage). For example, a wedge, wheel and axle, lever, inclined plane, screw, or pulley.

Spiral:   A curve that winds around a fixed center point (or axis) at a continuously increasing or decreasing distance from that point.

Tool:   A device used to do work.

Wedge:   A simple machine that forces materials apart. Used for splitting, tightening, securing or levering. It is thick at one end and tapered to a thin edge at the other.

Wheel and axle:   A simple machine that reduces the friction of moving by rolling. A wheel is a disk designed to turn around an axle passed through the center of the wheel. An axle is a supporting cylinder on which a wheel or a set of wheels revolves.

Work:   Force on an object multiplied by the distance it moves. W \u003d F x d (force multiplied by distance).

Associated activities

• Stack it up! - Students analyze and begin to design a pyramid. They perform calculations to determine the area of \u200b\u200btheir pyramid base, stone block volumes, the number of blocks required for their pyramid base, and make a scaled drawing of a pyramid on graph paper.
• Choosing a Pyramid Site - Working in engineering project teams, students choose a site for the construction of a pyramid. They base their decision on site features as provided by a surveyor "s report; distance from the quarry, river and palace; and other factors they deem important to the project.

Lesson closure

Today, we have discussed six simple machines. Who can name them for me? (Answer: Wedge, wheel and axle, lever, inclined plane, screw, and pulley.) How do simple machines make work easier? (Answer: Mechanical advantage enables us to use less force to move an object, but we have to move it a longer distance.) Why do engineers use simple machines? (Possible answers: Engineers creatively use their knowledge of science and math to make our lives better, often using simple machines. They invent tools that make work easier. They accomplish huge tasks that could not be done without the mechanical advantage of simple machines. They design structures and tools to use our environmental resources better and more efficiently.) Tonight, at home, think about everyday examples of the six simple machines. See how many you can find around your house!

Complete the KWL Assessment Chart (see the Assessment section). Gauge students "understanding of the lesson by assigning the Simple Machines Worksheet as a take-home quiz. As an extension, use the attached. Review the information and answer any questions. Suggest the students keep the sheet handy in their desks, folders or journals .

Lesson summary assessment

  Closing Discussion:   Conduct an informal class discussion, asking the students what they learned from the activities. Ask the students:

• Who can name the different types of simple machines? (Answer: Wedge, wheel and axle, lever, inclined plane, screw, and pulley.)
• How do simple machines make work easier? (Answer: Mechanical advantage enables us to use less force to move an object, but we have to move it a longer distance.)
• Why do engineers use simple machines? (Possible answers: Engineers creatively use their knowledge of science and math to make our lives better, often using simple machines. They invent tools that make work easier. They accomplish huge tasks that could not be done without the mechanical advantage of simple machines. They design structures and tools to use our environmental resources better and more efficiently.)

Remind students that engineers consider many factors when they plan, design and create something. Ask the students:

• What are the considerations an engineer must keep in mind when designing a new structure? (Possible answers: Size and shape (design) of the structure, available construction materials, calculation of materials needed, comparing materials and costs, making drawings, etc.)
• What are the considerations an engineer must keep in mind when choosing a site to build a new structure? (Possible answers: Site physical characteristics, distance to construction resources, suitability for the structure "s purpose.)

  KWL Chart (Conclusion):As a class, finish column L of the KWL Chart as described in the Pre-Lesson Assessment section. List all of the things they learned about simple machines. Were all of the W questions answered? What new things did they learn?

  Take-Home Quiz:Gauge students "understanding of the lesson by assigning the Simple Machines Worksheet as a take-home quiz.

Lesson extension activities

Use the attached Simple Machines Scavenger Hunt! Worksheet to conduct a fun scavenger hunt. Have the students find examples of all the simple machines used in the classroom and their homes.

Bring in everyday examples of simple machines and demonstrate how they work.

Illustrate the power of simple machines by asking students to do a task without using a simple machine, and then with one. For example, create a lever demonstration by hammering a nail into a piece of wood. Have students try to pull the nail out, first using only their hands

Bring in a variety of everyday examples of simple machines. Hand out one out to each student and have them think about what type of simple machine it is. Next, have students place the items into categories by simple machines and explain why they chose to place their item there. Ask students what life would be like without this item. Emphasize that simple machines make our life easier.

See the Edheads website for an interactive game on simple machines: http://edheads.org.

Engineering Design Fun with Levers: Give each pair of students a paint stirrer, 3 small plastic cups, a piece of duct tape and a wooden block or spool (or anything similar). Challenge the students to design a simple machine lever that will throw a ping pong ball (or any other type of small ball) as high as possible. In the re-design phase, allow the students to request materials to add on to their design. Have a small competition to see which group was able to send the ping pong ball flying high. Discuss with the class why that particular design was successful versus other variations seen during the competition.

Additional Multimedia Support

See http://edheads.org for a good simple machines website with curricular materials including educational games and activities.

References

Dictionary.com. Lexico Publishing Group, LLC. Accessed January 11, 2006. (Source of some vocabulary definitions, with some adaptation) http://www.dictionary.com

Simple Machines. inQuiry Almanack, The Franklin Institute Online, Unisys and Drexel eLearning. Accessed January 11, 2006. http://sln.fi.edu/qa97/spotlight3/spotlight3.html

Contributors

   Greg Ramsey; Glen Sirakavit; Lawrence E. Carlson; Jacquelyn Sullivan; Malinda Schaefer Zarske; Denise Carlson, with design input from the students in the spring 2005 K-12 Engineering Outreach Corps course

Copyright

   © 2005 by Regents of the University of Colorado.

Supporting program

   Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

Acknowledgments

The contents of these digital library curricula were developed by the Integrated Teaching and Learning Program under National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: February 11, 2019

(15 minutes)

• Distribute small toy cars that have wheels joined by axles to groups of students. Kick-start a discussion with some questions about the toy car mechanics, such as: How do these toy cars move? How are the wheels on each side of the car joined to each other?
• Have a student volunteer point to the rod that holds the two wheels together. Explain that the bar that joins two wheels is called an axle.
• Tell students that they will be learning about wheels and axles.
• Hold up the doorknob, explaining that it is an everyday example of a wheel and axle.
• Challenge the students to help you identify the wheel and axle in the doorknob. Listen as different students call out their guesses.
• After some speculation, tell students that the knob that turns is the wheel. The inner rod that is attached to the knob is the axle.
• Demonstrate how the wheel and axle works by turning the knob (wheel). That turns the inner rod (axle) and moves the latch, to open the door.

Guided practice

(15 minutes)

• To consolidate student thinking, set up activity stations with play dough and a rolling pin.
• Let students practice flattening the dough with the pin.
• Guide them to express these understandings: The rolling pin is a wheel and axle. When you push on the handles (the axle) the wheel turns and flattens out the dough.
• Challenge students to think of other common machines that have one wheel like the rolling pin. Great examples include a wheelbarrow, a top, and a playground merry-go-round.

Independent working time

(15 minutes)

• Pass out a copy of the Wheel and Axle worksheet to each student to complete independently.
• Walk around the classroom to offer support to students who get stuck.

Differentiation

• Enrichment:   Have students who need more of a challenge read a history of other simple machines, and fill out an accompanying word search.
• Support:   Put students who need more support into pairs to complete the Wheel and Axle worksheet.

Assessment

(10 minutes)

• Collect the worksheets that the students have filled out, and correct them using the Wheel and Axle answer sheet.

Review and closing

(5 minutes)

• In summary, remind students that the rolling pin is a wheel and axle. When you push on the handles (the axle) the wheel turns and flattens out the dough.
• Challenge students to think of other common machines that have one wheel like the rolling pin, such as a wheelbarrow, top, and merry-go-round.
• Remind your class that the wheel and axle is only one of six common simple machines that help things move. For homework or additional independent work, consider encouraging students to learn more about other kinds of simple machines.

Written in Perl. Some time later Yabb   was rewritten to Php   and began to be called YaBB SE.

As YaBB SE   developed, it became more and more, and by that time some aspects had appeared that required alteration and improvement of the project. It was decided that it was best to separate from YaBB SEbecause it was something other than YaBB. The most correct decision was to abandon everything that has been accumulated and start all over again. This is where development began. SMF.

September 29, 2003 the first version was released SMF 1.0 beta1, which was distributed only to the group Charter member. This was a big minus, since the forum could only use a limited circle of people who were part of this group. March 10, 2004 First Public Release Released SMF. Web Based Forums SMF 1.1: ami.lv and no less popular iratbildes.lv.

SMF   created as a replacement for the online forum YaBB SE, which has gained a bad reputation due to the problems of its counterpart developed on Perl   with a similar name - Yabb.

First versions Yabb   were known for performance issues and were resource intensive. YaBB SE   was written as an example Php-port Yabb, but at the same time he was less demanding on resources and even devoid of security problems.

SMF   started as a small project of one of the developers YaBB SE, and in order to expand the possibilities of templates YaBB SE. Since then, the project has gradually expanded: the general functionality “ordered” by users has been added, performance problems and security issues have been resolved.

Forum version 2.0 was announced on April 8, 2007. A public beta release was released on March 17, 2008. The main innovations include:

• Database abstraction: support planned PostgreSQL   and Sqlite.
• The moderation center, combining all moderation functions for all moderators, as well as allowing the moderation of topics, messages and attachments, if necessary.
• User Alert System
• Additional management of user groups such as moderators, as well as free and on-demand groups.
• Support Openid. Ability to use Openid-Account for registering and entering the forum.
• Additional fields in user profiles.
• WYSIWYGeditor to provide an intuitive user interface.
• Task Manager and Message Queuing System

The source code of the project is available in the public repository at Github   github.com/SimpleMachines/SMF2.1

License

SMF 1.0 and 1.1 are published under a proprietary license. While open source, the redistribution and / or distribution of modified components is limited to authorized bodies.

Simple Machines Forum version 2.0 and 2.1 licensed under BSD 3-p. It is also open source with redistribution of modified code depending on BSD requirements.

Localization

SMF Team

Over 50 people work on SMF, including:

• 3 managers
• 6 developers
• 3 documentaries

Team motto: “The few, the proud, the geeky!”

see also

Write a review on the article "Simple Machines Forum"

Notes

Literature

• Phil hughes    (Eng.) // Linux Journal. - 2008. - March 4.

References

•   - Official site Simple Machines Forum (English)
•   (Russian)
•   (Russian)

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Excerpt from the Simple Machines Forum

  According to the custodial affairs of the Ryazan estate, Prince Andrey had to see the district leader. The leader was Count Ilya Andreich Rostov, and Prince Andrei went to see him in mid-May.
  It was already a hot period of spring. The forest was already fully dressed, there was dust and it was so hot that, passing by the water, I wanted to swim.
Prince Andrei, unhappy and preoccupied with considerations of what and what he needed to ask the leader about business, drove up the alley of the garden to the Rostovs otradnensky house. To the right, from behind the trees, he heard a female, cheerful scream, and saw a crowd of girls running to cut his carriage. Ahead of the others, a black-haired, very thin, strangely thin, black-eyed girl in a yellow chintz dress, tied up with a white handkerchief, from which strands of combed hair were pulled out, ran up to the stroller. The girl screamed something, but when she recognized a stranger, without looking at him, she ran back with a laugh.
  Prince Andrew suddenly felt pain from something. The day was so good, the sun was so bright, everything was so fun all around; and this slender and pretty girl did not know and did not want to know about his existence and was pleased and happy with some kind of her own - truly stupid - but fun and happy life. “Why is she so glad? what is she thinking! Not about the military charter, not about the device of the Ryazan warriors. What is she thinking? And why is she happy? ”Prince Andrei involuntarily asked himself with curiosity.
  Count Ilya Andreich lived in Otradnoye in 1809 as before, that is, taking almost the entire province, with hunts, theaters, dinners and musicians. He, like any new guest, was glad to Prince Andrew, and almost forcibly left him to sleep.
  During a boring day, during which Prince Andrei was occupied by senior owners and the most honored guests, who, on the occasion of the approaching nameday, were filled with the house of the old count, Bolkonsky several times looking at Natasha laughing and having fun between the other young half of society, asked himself: "What is she thinking? Why is she so glad! "
  In the evening, left alone in a new place, he could not sleep for a long time. He read, then put out the candle and lit it again. It was hot in a room with shutters closed inside. He was annoyed at this stupid old man (as he called Rostov), \u200b\u200bwho detained him, assuring that the necessary papers in the city had not been delivered yet, he was annoyed at himself for remaining.
Prince Andrey got up and went to the window to open it. As soon as he opened the shutters, the moonlight, as if he was on guard at the window had long been waiting for this, burst into the room. He opened the window. The night was fresh and still bright. In front of the window was a row of trimmed trees, black on one and silver-lit on the other. Under the trees there was some kind of lush, wet, curly vegetation with silver leaves and stems in some places. Further, behind the ebony trees there was a kind of shiny dew roof, to the right of a large curly tree, with a brightly white trunk and branches, and above it there was an almost full moon in a bright, almost starless, spring sky. Prince Andrei leaned on the window and his eyes rested in that sky.
  Prince Andrew's room was on the middle floor; in the rooms above him they also lived and did not sleep. He heard a female dialect from above.
  “Just one more time,” said the female voice from above, which Prince Andrey now recognized.
  - But when will you sleep? - answered another voice.
  - I won’t, I can’t sleep, what can I do! Well, the last time ...
  Two female voices sang some sort of musical phrase that made up the end of something.
  - Oh, what a delight! Well now to sleep, and the end.
  “You sleep, but I can’t,” answered the first voice, approaching the window. She apparently completely leaned out the window, because she could hear the rustling of her dress and even breathing. Everything was quiet and petrified, like the moon and its light and shadows. Prince Andrey was also afraid to move, so as not to betray his involuntary presence.
  - Sonya! Sonia! - the first voice was heard again. - Well, how can you sleep! Yes, look what a charm! Ah, what a delight! Wake up, Sonya, ”she said, almost with tears in her voice. - After all, such a lovely night has never, never happened.
  Sonya reluctantly answered something.
  “No, look at the moon! ... Ah, what a delight!” You come here. Darling, my dear, come here. Well, see? So I would have squatted down, like that, I would have grabbed myself under my knees, - as tight as possible - it is necessary to strain. Like this!
  “Full, you will fall.”
  There was a struggle and Sonya’s displeased voice: “After all, the second hour.”
  - Ah, you just spoil everything for me. Well, go, go.
  Again, everything was silent, but Prince Andrei knew that she was still sitting there, he sometimes heard quiet movements, sometimes sighs.
  - Oh my god! Oh my God! what is it! She cried out suddenly. - Sleep so sleep! - and slammed the window.
“And it doesn’t matter to my existence!” Thought Prince Andrei while he was listening to her dialect, for some reason waiting and afraid that she would say something about him. - “And again she! And how deliberate! ”He thought. Such an unexpected confusion of young thoughts and hopes, contradicting his whole life, suddenly rose in his soul that he, feeling unable to understand his condition, immediately fell asleep.

The next day, having said goodbye to only one count, before waiting for the ladies to leave, Prince Andrey went home.
  It was already early June, when Prince Andrei, returning home, rode into that birch grove again, in which this old, clumsy oak tree so strangely and impressively struck him. The bells were still ringing in the woods less than a month and a half ago; everything was full, shady and thick; and young spruce, scattered throughout the forest, did not violate the general beauty and, falsifying themselves as a general character, tenderly turned green with fluffy young shoots.
  The whole day was hot, where a thunderstorm was gathering, but only a small cloud sprayed on the dust of the road and on lush leaves. The left side of the forest was dark, in the shade; the right wet, glossy one shone in the sun, swaying slightly from the wind. Everything was in bloom; nightingales rattled and rolled close and far.
  "Yes, here, in this forest, there was this oak tree, with which we agreed," thought Prince Andrew. “Yes, where is he,” Prince Andrew thought again, looking at the left side of the road and without knowing it, without recognizing him, he admired the oak tree he was looking for. The old oak tree, all transformed, spreading out with a tent of lush, dark greenery, thinned, swaying a little in the rays of the evening sun. No gnarled fingers, no sores, no old distrust and grief - nothing was visible. Juicy, young leaves made their way through the stiff, hundred-year-old bark without knots, so it was impossible to believe that this old man produced them. “Yes, this is the same oak,” thought Prince Andrew, and suddenly he found an unreasonable, springy sense of joy and renewal on him. All the best moments of his life suddenly at the same time he remembered. And Austerlitz with a high sky, and the dead, reproached face of his wife, and Pierre on the ferry, and the girl, excited by the beauty of the night, and this night, and the moon - and all this he suddenly remembered.

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• Simple Machines for Kids: Science and Engineering for Children - FreeSchool

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  Transcription

  You "re watching FreeSchool! Hi everyone! Today we" re going to talk about simple machines. A simple machine is a device that makes work easier by magnifying or changing the direction of a force. That means that simple machines allow someone to do the same work with less effort! Simple machines have been known since prehistoric times and were used to help build the amazing structures left behind by ancient cultures. The Greek philosopher Archimedes identified three simple machines more than 2,000 years ago: the lever, the pulley, and the screw. He discovered that a lever would create a mechanical advantage, which means that using a lever would allow a person to move something that would normally be too heavy for them to shift. Archimedes said that with a long enough lever and a place to rest it, a person could move the world. Over the next few centuries more simple machines were recognized but it was less than 450 years ago that the last of the simple machines, the inclined plane, was identified. There are six types of simple machines: the Lever, the Wheel and Axle, the Pulley, the Inclined plane, the Wedge, and the Screw. Pulleys and Wheel and Axles are both a type of Lever. Wedges and Screws are both types of Inclined Planes. Each type of Simple Machine has a specific purpose and way they help do work. When speaking of simple machines, "work" means using energy to move an object across a distance. The further you have to move the object, the more energy it takes to move it. Let "s see how each type of simple machine helps do work. A LEVER is a tool like a bar or rod that sits and turns on a fixed support called a fulcrum. When you use a lever, you apply a small force over a long distance, and the lever converts it to a larger force over a shorter distance. Some examples of levers are seesaws, crowbars, and tweezers. A Wheel and Axle is easy to recognize. It consists of a wheel with a rod in the middle. You probably already know that it "s easier to move something heavy if you can put it in something with wheels, but you might not know why. For one thing, using wheels reduces the friction - or resistance between surfaces - between the load and the ground. Secondly, much like the lever, a smaller force applied to the rim of the wheel is converted to a larger force traveling a smaller distance at the axle. Wheel and axles are used for machines such as cars, bicycles, and scooters, but they are also used in other ways, like doorknobs and pencil sharpeners. A Pulley is a machine that uses a wheel with a rope wrapped around it. The wheel often has a groove in it, which the rope fits into. One end of the rope goes around the load, and the other end is where you apply the force. Pulleys can be used to move loads or change the direction of the force you are using, and help make work easier by allowing you to spread a weaker force out along a longer path to accomplish a job. By linking multiple pulleys together, you can do the same job with even less force, because you are applying the force along a much longer distance. Pulleys may be used to raise and lower flags, blinds, or sails, and are used to help raise and lower elevators. An Inclined Plane is a flat surface with one end higher than the other. Inclined planes allow loads to slide up to a higher level instead of being lifted, which allows the work to be accomplished with a smaller force spread over a longer distance. You may recognize an inclined plane as the simple machine used in ramps and slides. A Wedge is simply two inclined planes placed back to back. It is used to push two objects apart. A smaller force applied to the back of the wedge is converted to a greater force in a small area at the tip of the wedge. Examples of wedges are axes, knives, and chisels. A Screw is basically an inclined plane wrapped around a pole. Screws can be used to hold things together or to lift things. Just like the inclined plane, the longer the path the force takes, the less force is required to do the work. Screws with more threads take less force to do a job since the force has to travel a longer distance. Examples of screws are screws, nuts, bolts, jar lids, and lightbulbs. These six simple machines can be combined to form compound or complex machines, and are considered by some to be the foundation of all machinery. For example, a wheelbarrow is made of levers combined with a wheel and axle. A pair of scissors is another complex machine: the two blades are wedges, but they are connected by a lever that allows them to come together and cut. We use simple machines to help us do work every day. Every time you open a door or a bottle, cut up your food, or even just climb stairs, you are using simple machines. Take a look and see if you can identify the simple machines around you and figure out how they make it easier to do work.

  Contents

History

The idea of \u200b\u200ba simple machine originated with the Greek philosopher Archimedes around the 3rd century BC, who studied the Archimedean simple machines: lever, pulley, and screw. He discovered the principle of mechanical advantage in the lever. Archimedes "famous remark with regard to the lever:" Give me a place to stand on, and I will move the Earth. "(Greek: δῶς μοι πᾶ στῶ καὶ τὰν γᾶν κινάσω ) expresses his realization that there was no limit to the amount of force amplification that could be achieved by using mechanical advantage. Later Greek philosophers defined the classic five simple machines (excluding the inclined plane) and were able to roughly calculate their mechanical advantage. For example, Heron of Alexandria (ca. 10–75 AD) in his work Mechanics   lists five mechanisms that can "set a load in motion"; lever, windlass, pulley, wedge, and screw, and describes their fabrication and uses. However the Greeks "understanding was limited to the statics of simple machines; the balance of forces, and did not include dynamics; the tradeoff between force and distance, or the concept of work.

Strictionless analysis

Although each machine works differently mechanically, the way they function is similar mathematically. In each machine, a force    F in (\\ displaystyle F _ (\\ text (in)) \\,)   is applied to the device at one point, and it does work moving a load,    F out (\\ displaystyle F _ (\\ text (out)) \\,)   at another point. Although some machines only change the direction of the force, such as a stationary pulley, most machines multiply the magnitude of the force by a factor, the mechanical advantage

   M A \u003d F out / F in (\\ displaystyle \\ mathrm (MA) \u003d F _ (\\ text (out)) / F _ (\\ text (in)) \\,)

that can be calculated from the machine "s geometry and friction.

The mechanical advantage can be greater or less than one:

• The most common example is a screw. In most screws, applying torque to the shaft can cause it to turn, moving the shaft linearly to do work against a load, but no amount of axial load force against the shaft will cause it to turn backwards.
• In an inclined plane, a load can be pulled up the plane by a sideways input force, but if the plane is not too steep and there is enough friction between load and plane, when the input force is removed the load will remain motionless and will not slide down the plane, regardless of its weight.
• A wedge can be driven into a block of wood by force on the end, such as from hitting it with a sledge hammer, forcing the sides apart, but no amount of compression force from the wood walls will cause it to pop back out of the block.

A machine will be self-locking if and only if its efficiency η   is below 50%:

   η ≡ F o u t / F i n d i n / d o u t< 0.50 {\displaystyle \eta \equiv {\frac {F_{out}/F_{in}}{d_{in}/d_{out}}}<0.50\,}

Whether a machine is self-locking depends on both the friction forces (coefficient of static friction) between its parts, and the distance ratio d in / d out   (ideal mechanical advantage). If both the friction and ideal mechanical advantage are high enough, it will self-lock.

Proof

When a machine moves in the forward direction from point 1 to point 2, with the input force doing work on a load force, from conservation of energy the input work    W 1,2 (\\ displaystyle W _ (\\ text (1,2)) \\,)   is equal to the sum of the work done on the load force    W load (\\ displaystyle W _ (\\ text (load)) \\,)   and the work lost to friction

   W 1,2 \u003d W load + W fric (1) (\\ displaystyle W _ (\\ text (1,2)) \u003d W _ (\\ text (load)) + W _ (\\ text (fric)) \\ qquad \\ qquad (1 ) \\,)

If the efficiency is below 50%    η \u003d W load / W 1,2< 1 / 2 {\displaystyle \eta =W_{\text{load}}/W_{\text{1,2}}<1/2\,}

   2 W load< W 1,2 {\displaystyle 2W_{\text{load}}    2 W load< W load + W fric {\displaystyle 2W_{\text{load}}    W load< W fric {\displaystyle W_{\text{load}}

When the machine moves backward from point 2 to point 1 with the load force doing work on the input force, the work lost to friction    W fric (\\ displaystyle W _ (\\ text (fric)) \\,)   is the same

   W load \u003d W 2,1 + W fric (\\ displaystyle W _ (\\ text (load)) \u003d W _ (\\ text (2,1)) + W _ (\\ text (fric)) \\,)

So the output work is

   W 2.1 \u003d W load - W fric< 0 {\displaystyle W_{\text{2,1}}=W_{\text{load}}-W_{\text{fric}}<0\,}

Thus the machine self-locks, because the work dissipated in friction is greater than the work done by the load force moving it backwards even with no input force

Modern machine theory

Kinematic chains

Classification of machines

The identification of simple machines arises from a desire for a systematic method to invent new machines. Therefore, an important concern is how simple machines are combined to make more complex machines. One approach is to attach simple machines in series to obtain compound machines.

However, a more successful strategy was identified by Franz Reuleaux, who collected and studied over 800 elementary machines. He realized that a lever, pulley, and wheel and axle are in essence the same device: a body rotating about a hinge. Similarly, an inclined plane, wedge, and screw are a block sliding on a flat surface.

This realization shows that it is the joints, or the connections that provide movement, that are the primary elements of a machine. Starting with four types of joints, the revolute joint, sliding joint, cam joint and gear joint, and related connections such as cables and belts, it is possible to understand a machine as an assembly of solid parts that connect these joints.

See also

References

1.   Chambers, Ephraim (1728), "Table of Mechanicks", Cyclopædia, A Useful Dictionary of Arts and Sciences, London, England, Volume 2, p. 528, Plate 11.
2.   Paul, Akshoy; Roy, Pijush; Mukherjee, Sanchayan (2005), Mechanical sciences: engineering mechanics and strength of materials, Prentice Hall of India, p. 215, ISBN.
3. ^   Asimov, Isaac (1988), Understanding physics   , New York, New York, USA: Barnes & Noble, p. 88, ISBN.
4.   Anderson, William Ballantyne (1914). Physics for Technical Students: Mechanics and Heat   . New York, USA: McGraw Hill. pp. 112–122. Retrieved 2008-05-11 .
5. ^ Compound machines   , University of Virginia Physics Department, retrieved 2010-06-11 .
6. ^   Usher, Abbott Payson (1988). A History of Mechanical Inventions   . USA: Courier Dover Publications. p. 98. ISBN.
7.   Wallenstein, Andrew (June 2002). . Proceedings of the 9th Annual Workshop on the Design, Specification, and Verification of Interactive Systems. Springer p. 136. Retrieved 2008-05-21 .
8. ^   Prater, Edward L. (1994), Basic machines   (PDF), U.S. Navy Naval Education and Training Professional Development and Technology Center, NAVEDTRA 14037.
9.   U.S. Navy Bureau of Naval Personnel (1971), Basic machines and how they work   (PDF), Dover Publications.
10.   Reuleaux, F. (1963), The kinematics of machinery (translated and annotated by A.B.W. Kennedy), New York, New York, USA: reprinted by Dover.
11.   Cornell University, Reuleaux Collection of Mechanisms and Machines at Cornell University   , Cornell University.
12. ^   Chiu, Y. C. (2010), An introduction to the History of Project Management   , Delft: Eburon Academic Publishers, p. 42,