Answer
(a) $-0.86J$
(b) greater than
(c) $-1.2J$
Work Step by Step
(a) We can find the required potential energy as
$U=0+mg\Delta y$
$U=mg(-Lcos\theta -0)$
We plug in the known values to obtain:
$U=-(0.13)(9.81)(0.95)cos45^{\circ}$
$U=-0.86J$
(b) We know that the magnitude of the change in potential energy form $90^{\circ}$ to $45^{\circ}$ is greater than the magnitude of the change from $45^{\circ}$ to $0^{\circ}$ because most of the height changes between $90^{\circ}$ and $45^{\circ}$.
(c) We can find the required potential energy as
$U=0+mg\Delta y$
$\implies U=mg(-L-0)$
We plug in the known values to obtain:
$U=-(0.13)(9.81)(0.95)$
$U=-1.2J$
