conservation of momentum?

Question

a cart moving on smooth horizontal track without any external force.rain is falling with a velocity u m/s at an angle theta (clockwise) with the vertical.rain drops are collected in the car at the rate of m kg/s.if the initial mass of the car is M and velocity V(towards right) then find its velocity after time T

Answer 1

All you need to worry about is the horizontal component of the rain's momentum, which is (m kg /s)(sin theta)(t) if theta is measured from the vertical.

Final momentum = initial momentum + change in momentum

(M + mt)v = MV + (m )(sin theta)(t)

Solve for v, the final velocity of the system.