A tennis player hits a 58.0 {\rm g} tennis ball so that it goes straight up and reaches a maximum height of 7.35 {\rm m} .How much work does gravity do on the ball on the way up?

Respuesta :

The answer is -4.18 J

A work (W) is a product of a force (F) and a distance (d): W = - F · d (negative because it goes way up, against the gravitation)
Since the force is a product of mass and acceleration: F = m · a
then work would be: W = - m · a · h
It is known:
m = 58 g = 0.058 kg
h = 7.35 m
a = 9.8 m/s² (gravitational acceleration, since is expected that on some height gravitation force will work).

Therefore,
W = - 0.058 * 7.35 * 9.8 = -4.18 J
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