Work and Machines

# Work and Machines -...

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1.  How would the effort exerted by a backpacker over  level ground compare to the effort in climbing a steep  hill? 2.  How would the weight of the backpack affect the  amount of force needed to move it?

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Work and Machines A. Work 1. The transfer of energy when a force makes an object move. 2. W = f ·d Box being given energy 3. Energy is transferred between objects when work is done. (Unit is a joule or N ·m)
B. Power 1. The rate at which work is done. 2. P = W / t 3. Unit is the watt (1 joule / second) 4. Btu = 1,055 watts (for heating and cooling units) 5. Horsepower = 746 watts (for motors and engines)

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C. Using Machines 1. A machine makes doing work easier. 2. They may multiply the applied force. The car may weigh a lot, but  you don’t have to use nearly  that much force to lift it  with a jack.
They may increase the distance over which a force is applied. In this case, the amount of force necessary to push the chair up

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## This note was uploaded on 11/22/2011 for the course EL ED 302 taught by Professor Staff during the Winter '08 term at BYU.

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Work and Machines -...

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