p08_007.pdf

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Chapter 8 - 8.7
d ,where F is the force
and d is the displacement. The force is vertically downward and has magnitude mg ,where m is
the mass of the snowball. The expression for the work reduces to W = mgh ,where h is the height
through which the snowball drops. Thus
·
W = mgh =(1 . 50 kg)(9 . 8m / s 2 )(12 . 5m) = 184 J .
184 J.
(c) The potential energy when it reaches the ground is less than the potential energy when it is fired
by
−
W =
−
∆ U
,so U =
−
184 J when the snowball hits the ground.
7. (a) The force of gravity is constant, so the work it does is given by W = F
(b) The force of gravity is conservative, so the change in the potential energy of the snowball-Earth
system is the negative of the work it does: ∆ U =
|
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