Answer
a) 1.07 J
b) 1.12 J
Work Step by Step
We have to find the height of the 0 potential energy, which is in the middle of the brick. Thus, we find the middle of the brick's height originally:
$h = \frac{.055}{2}=.0275 \ m$
For the next parts of the problem, we find how much the center of the brick is above the point of 0 potential energy:
a) $U=mgh=(1.5)(9.81)(\frac{.2}{2}-.0275)=1.07 \ J$
b) $U=mgh=(1.5)(9.81)(.104-.0275)=1.12 \ J$
