Answer
–167 J
Work Step by Step
We use the equation for the change in potential energy $\Delta$U = mg$\Delta$h, where m is mass in kg, g = 9.8 m/$s^{2}$ and $\Delta$h is the change in height. In this scenario, the distance the book falls is $\Delta$h = –(10.0 m – 1.50 m) = –8.50 m, because it’s dropped 10.0 m above the ground but it’s caught 1.50 m above the ground. The change is negative because the book is being dropped, and thus the height is being reduced.
Plugging in this information along with the given mass of 2.0 kg, we get:
$\Delta$U = mg$\Delta$h
= (2.00 kg)(9.8 m/$s^{2}$)(–8.50 m)
= –167 J (rounded to 3 significant figures)
