Work and machines Topic

Work and machines

Science, Grade 3

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Study Guide Work and machines Science, Grade 3

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WORK AND MACHINES Work is when you use force upon an object causing the object to move. The amount of work you do has to do with how much force you need to use and how far you move an object. You would do more work lifting a heavy desk than you would lifting a pencil. If you do not move an object, no matter how hard you push or pull, NO work is being done. Which means, in order for work to be done, an object needs to move. Simple machines make doing work easier but they never decrease the amount of work that needs to be done. There are many different kinds of simple machines. An inclined plane is a simple machine that connects a higher area to a lower area. An inclined plane allows you to move an object up or down by rolling or sliding it without lifting the object directly. A ramp is an example of an inclined plane. © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.

A wedge is a simple machine made of wood or metal that has a pointed edge and two slanted sides. A wedge is actually two inclined planes put together. A wedge is often used to split wood, to cut things, or to hold things together. Lesson checkpoint: Where have you seen a wedge used before? A screw is an inclined plane that is wrapped around a nail. Screws are mainly used to fasten things together tightly. A lever is a simple machine that is a stiff bar, which rests and moves on a fixed point. You can push down on one side to raise an object on the other side. See saw is an example of a lever. © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.

A wheel and axle is a simple machine made up of a pole and a wheel that revolves, or turns, around on the pole to move something. A door knob is an example of a wheel and axle, where the knob moves the lock so you can open the door. Lesson checkpoint: What is an example of a wheel and axle? A pulley is another simple machine that helps lift heavy loads. In a pulley, you pull a rope that runs around a wheel with a grooved rim; the object you want to lift is at the other end of the rope. When you use a pulley you can use your own body weight to help raise an object by pulling the object up with the rope. There are two kinds of pulleys. A fixed pulley is attached to the load and moves with the load as the rope is pulled. A moveable pulley is attached to a non-moving structure above the load. © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.