1) A machine is a device that makes work easier or more effective by changing the amount of force needed, the distance over which force is applied, or the direction of the applied force. 2) When using a machine, the input work (force x distance applied by the user) equals the output work (force x distance applied by the machine). Machines can make work easier by either increasing distance to reduce necessary force, or by increasing force to reduce the distance needed. 3) Examples of machines that change force include ramps and levers. Examples that change distance include hockey sticks and chopsticks. Some machines like pulleys change the direction of applied force to make work easier.

1. Machines

4. Shovels and rakes make the work of these students easier.

10. Output Work The shovel exerts a small output force over a large output distance. . Input Work The gardener exerts a large input force over a small input distance Large In. Force + Small In. Distance = Small Out. Force + Large Out. Distance

14. A faucet knob changes force in the same way. You need a small amount of force to turn the knob but you must twist it many times so that it can exert a large amount of force to open the valve inside. The valve needs to open only a small amount in order for the water stream to flow.

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