# Work and Power

### Problems

Problem :

An elevator must lift 1000 kg a distance of 100 m at a velocity of 4 m/s. What is the average power the elevator exerts during this trip?

Problem :

An object in free fall is said to have reached terminal velocity if the air resistance becomes strong enough to counteract all gravitational acceleration, causing the object to fall at a constant speed. The exact value of the terminal velocity varies according to the shape of the object, but can be estimated for many objects at 100 m/s. When a 10 kg object has reached terminal velocity, how much power does the air resistance exert on the object?

Problem :

Calculus based problem Derive, using the equation P = , an expression for the power exerted by gravity on an object that is in free fall.

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