Answer
(a) $0.91J$
(b) $4.0min$
Work Step by Step
(a) We can find the required energy as follows:
$E=(I\Delta t)V$
We plug in the known values to obtain:
$E=(7.5mA)(35s)(3.5V)$
$E=0.91J$
(b) We can find the required time as
$\Delta t=\frac{mgh}{VI}$
We plug in the known values to obtain:
$\Delta t=\frac{(0.65Kg)(9.8m)(1.0m)}{(3.5V)(7.5\times 10^{-3}A)}$
$\Delta t=243s=4.0min$
