Answer
After 60.0 minutes, the car's speed is 7.26 m/s
Work Step by Step
We can find the mass of snow $m_s$ that falls into the car in 60.0 minutes.
$m_s = (3.80~kg/min)(60.0~min) = 228~kg$
We can then use conservation of momentum to find the final speed $v$,
$m_1~v_1 = (m_1+m_s)~v$
$v = \frac{(4800~kg)(7.60~m/s)}{(4800~kg+228~kg)}$
$v = 7.26~m/s$
After 60.0 minutes, the car's speed is 7.26 m/s
