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# Work and energy: Man on an escalator; speed that arrow leaves the bow; work done on a basketball by air resistance

A 72.0-kg man is riding an escalator in a shopping mall. The escalator moves the man at a constant velocity from ground level to the floor above, a vertical height of 3.70 m. What is the work done on the man by (a) the gravitational force and (b) the escalator?

A 82.8-g arrow is fired horizontally from rest. The bowstring exerts an average force of 62.5 N on the arrow over a distance of 0.908 m. With what speed does the arrow leave the bow?

A basketball player makes a jump shot. The 0.610-kg ball is released at a height of 2.23 m above the floor with a speed of 7.85 m/s. The ball goes through the net 3.29 m above the floor at a speed of 5.25 m/s. What is the work done on the ball by air resistance, a nonconservative force?

#### Solution Preview

1.
W=F*S where the displacement is pointint upward.
(a)
For the gravational force, it is pointing downward. ...

#### Solution Summary

With full formulas and calculations, the problems are solved.

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