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# Work on a Falling Rock

APPH12-X4WZLD

A $10 \text{ kg}$ rock is thrown directly downward off a cliff ($h = 100\text{ m}$) with an initial velocity of $5\text{ m/s}$. Just before striking the ground, the rock has a velocity of $44.294\text{ m/s}$.

Assuming $g=9.81 \text{ m/s}^2$, how much work was done by frictional forces?

A

$0\text{ J}$; There are no frictional forces acting on the rock.

B

$9810\text{ J}$

C

$125\text{ J}$

D

$1962\text{ J}$