Answer
a) $a= \frac{v_0dm}{Mdt}$
b) The maximum speed of the car will be equal to the speed of the water initially.
Work Step by Step
a) We find:
$F=\frac{dp}{dt} \\ F=v_0 \frac{dm}{dt}$
Using Newton's second law, it follows:
$a= \frac{v_0dm}{Mdt}$
b) Since the water bounces up at the same speed it hits at, we find that $\fbox{the maximum speed of the car will be equal to the speed of the water initially.}$
