Work & Machines

Science, Grade 3

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Work and Machines Inclined Plane Wheel and Axle Screw Wedge Lever Pulley Bikes move by using wheels and axles, too. fixed pulley moveable pulley In science, work is when you use force upon an object causing the object to move. The amount of work you do depends on how much force you use and how far you move an object. You do more work lifting up a heavy desk than lifting up a pencil. If you do not move an object, no matter how hard you push or pull, no work is being done. In order for work to be done, an object needs to move. © Copyright NewPath Learning. All Rights Reserved. 94-4309 www.newpathlearning.com 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 is a plane or a ramp that connects a higher area to a lower area. This simple machine allows you to move an object up or down by rolling or sliding it without lifting the object directly. 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. 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. A see saw is an example of a lever. A hammer can also be used as a lever. A pulley is a simple machine that is made up of a wheel with a grooved rim in which a rope can move around in order to help lift a load. When you use a pulley you can use your own body weight to help raise an object by pulling the object up. There are two kinds of pulleys. A movable pulley is attached to the load and moves with the load as the rope is pulled. A fixed pulley is attached to a non-moving structure above the load. A wheel and axle is a simple machine made up of a pole and a wheel that revolves or turns around on the pole. A door knob is an example of a wheel and axle. inclined plane Forces - How Simple Machines Work input force output force input force output force output force output force input force input force output force
Work and Machines Inclined Plane Wheel and Axle Screw Wedge Bikes move by using wheels and axles, too. How do scientists define work? ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ What do simple machines allow you to do? ___________________________________________________________ ___________________________________________________________ Forces - How Simple Machines Work input force output force input force output force output force output force input force input force output force Describe an inclined plane: ________________________________ ________________________________ ________________________________ Describe a screw: ________________________ ________________________ ________________________ Describe a wheel and axle: _______________ _______________ _______________ _______________ Describe a wedge: ________________________________ ________________________________ _________________________ Key Vocabulary Terms fixed pulley force inclined plane lever movable pulley pulley screw simple machines wedge wheel and axle work Lever Describe a lever: _____________________________ _____________________________ _____________________ _____________________ Pulley Describe a pulley: ____________ _____________________ _____________________ How is a movable pulley different from a fixed pulley? _____________________________ _____________________________ © Copyright NewPath Learning. All Rights Reserved. 94-4309 www.newpathlearning.com \|xiBAHBDy01740qzZ