A person looking down a window of a stationary train notices that raindrops are falling vertically down at a?

Question

speed of 5.0m/s relative to the ground. When the train moves at a constant velocity, the raindrops make an angle of 25 degress when they move past the window, as the drawing shows. How fast is the train moving?

Answer 1

Unfortunately I can't see the drawing. What the drawing would tell me, and you didn't, is whether the 25 deg is relative to the vertical or the horizontal. I'm going to take a guess that it's relative to the horizontal, because if it were to the vertical the train would be moving pretty slowly. So we have a right triangle with the sides adjacent to the right angle being the vertical speed of the rain and the horizontal speed of the train. The acute 25 deg angle is at one end of the horizontal speed side. The train speed = rain speed / arctan(25 deg).