Abstract

Objective

To determine and rank the number of simple machines in common toys.

Introduction

Click here to watch a video of this investigation, produced by DragonflyTV and presented by pbskidsgo.org.

Did you know that you used a simple machine today? Yes, that's right, if you used a knife or a fork to eat your lunch, you used a simple machine called a wedge. If you used chopsticks instead, you used a simple machine called a lever. Simple machines are in every part of your daily life, from the zippers on your clothes to the hinged doors you walk through, to the sloped bottom of your bathtub. Simple machines are there to make your life easier.

So now you know that a simple machine can bring food to your mouth and close a coat, but can it do something really hard, like lift a gigantic rock? The answer is yes! If you want to see how, just take a look at the DragonflyTV video at the right, and you’ll join Aaron and Tevi as they visit a modern construction marvel, the Coral Castle, in Florida, and learn how to move huge boulders with just muscle power and a simple machine!

What are simple machines? They are devices that change either the direction or the size of a force. A force is a push or a pull that can make an object change its velocity. For example, with a simple machine like a pulley, you can lift many more pounds than you normally could by yourself. The pulley increases the size of the force you are able to apply to the object that you are trying to lift. Throughout history, people have used simple machines to build structures that seem impossible to construct without modern heavy equipment. The Great Pyramids of Egypt (built in 2570 BC), Stonehenge in England (built in 3100 BC), and Machu Picchu in Peru (built in 1450 AD and shown below) are all examples of extraordinary structures that were built with simple machines.

Figure 1. These photos show an ancient structure in Peru, called Machu Picchu, that was built with the help of simple machines. (Lisa Urness, 2008.)

Simple machines fall into two groups: Those that balance twists (torques) and those that balance forces (pushes and pulls). Levers, pulleys, and wheels balance torques, while inclined planes, wedges, and screws balance forces. Descriptions and examples of these six simple machines are shown in the table below:

Simple Machine	What does it look like?	What does it do?	Examples
Lever	A stiff bar, rod, or plank that sits on or moves about a fulcrum	Lifts or moves things	Human arm, baseball bat, boat paddle, broom, chopsticks, door, fishing rod, hockey stick, tongs, tweezers, mousetrap, nail clippers, shovel, wheelbarrow, diving board, crowbar, oars, seesaw, scissors, bicycle brakes, stapler, door on hinges, seesaw, hammer, bottle opener
Pulley	One or more grooved wheels with a rope or cable inside the groove	Moves things up or down or across	Flag pole, crane, blinds, sailboat, clothes line
Wheel and axle	One or two wheels attached to a rod called an axle	Moves loads or transfers rotational forces	Door knob, wagon, toy car, pencil sharpener, gears (special type of toothed wheels)
Inclined plane	A sloping surface that connects a higher level to a lower level	Moves things up or down	Ramp, chute, slide
Wedge	A triangular-shaped tool	Cuts or splits things apart	Axe, zipper, knife, fork, nail, chisel, pin, snowplow
Screw	A circular inclined plane; an inclined plane wrapped around a pole	Holds things together or lifts	Bolt, spiral staircase, jar lids, lightbulbs, stools, key rings, wrenches

Table 1. This table shows the types of simple machines.

Simple machines are called simple because they are like the building blocks from which other, more complex machines, are made. For example, a bicycle is a complex machine made up of four types of simple machines: levers, pulleys, screws, and wheels. A wheelbarrow and a can opener are also examples of more complex machines that are made up of two or more simple machines.

So now that you've seen that there are many simple machines all over your house, it's time to check your toy box! How many can you find hiding in there? Is there a lever lurking in your baseball bat? An inclined plane on your racetrack? A wheel and axle in your pony carriage? It's time to find out!

Terms, Concepts, and Questions to Start Background Research

• Wedge
• Lever
• Force
• Velocity
• Pulley
• Torque
• Wheel
• Inclined plane
• Wedge
• Screw
• Fulcrum

Questions

• What is a simple machine?
• Why are simple machines important?
• What are the types of simple machines?

Bibliography

This science fair project was inspired by this resource:

• TPT. (2006). Coral Castle by Aaron and Tevi. DragonflyTV, Twin Cities Public Television. Retrieved July 2, 2008, from http://pbskids.org/dragonflytv/show/coralcastle.html

This source describes and provides examples of simple machines:

• Wikipedia Contributors. (2008, July 2). Simple machine. Wikipedia: The Free Encyclopedia. Retrieved July 2, 2008, from http://en.wikipedia.org/w/index.php?title=Simple_machine&oldid=223017881

For help creating graphs, try this website:

• National Center for Education Statistics (n.d.). Create a Graph. Retrieved May 23, 2008, from http://nces.ed.gov/nceskids/createAGraph/

Materials and Equipment

• Toys (at least ten)
• Lab notebook
• Digital camera (optional)

Experimental Procedure

1. Get ten toys from your toy box, play area, or yard and put them in a well-lit area so you can look at them carefully. Write down the name of the toys in a data table in your lab notebook, like the one below.
2. Take photographs of the toys, if desired, for your display board.
3. Carefully look at your toys. Try to see how they work. Are there hinged doors (which are levers)? Are there ramps or slides (which are inclined planes)? Is there one wheel that rotates another wheel (this would be a gear—a special type of wheel and axle)? If you look at a bicycle, for example, you'll see screws holding all the parts together. Then there are levers in the handles, gear shifts, brake handles, and pedals, and the pedals turn a pulley. Try to count how many simple machines there are in each toy you have selected and write down your counts in your data table.

   Number of Simple Machines in My Toys
   Toy Name	Bicycle										Total Count
   Lever Count
   Pulley Count
   Wheel and Axle Count
   Inclined Plane Count
   Wedge Count
   Screw Count

4. Look at your data table after you have filled it out, and add up the counts across each row for each simple machine. Write down the total counts in the last column. Which simple machine was used the most in your toys? Which simple machine was used the least? Rank the simple machines from most-used to least-used, and, if desired, make a bar chart showing each type of simple machine on the x-axis and the number of times each was used in your toys on the y-axis. You can make the bar chart by hand, or use an online graphing tool like Create a Graph. If you took photographs of your toys for your display board, print out the photos and label the simple machines that you found on each photo.

Variations

• Design and build a device made of two or more simple machines that completes a task you would like to have done.

• For more science project ideas in this area of science, see Mechanical Engineering Project Ideas.

Credits

Kristin Strong, Science Buddies

Last edit date: 2008-10-31 11:00:00