Raindrops striking car - find impulse

I have this exercise of many i have to do but this is the hardest of them and i don't get it much.


While a car is stopped at a traffic light in a storm, raindrops strike the roof of the car. The area of the roof is 5.0 m^2. Each raindrop has a mass of 3.7 x 10^-4 Kg and speed of 2.5 m/s before impac6 and is at rest after impact. If, on average at given time, 150 raindrops strike each square meter, what is the impulse of the rain striking the car?


is there a formula for this or something? This physic class is driving me crazy, i understand the lab but the class professor (is different than the lab one) is old doesn't explain too well and im just lost.