1. The problem statement, all variables and given/known data A tube is mounted on a flat cart which is in uniform motion on a horizontal plan. How must the tube be orientated on the car in order for rain drops, falling vertically, to miss hitting the walls when falling inside the tube? The motion of the rain drops is assumed uniform. 2. Relevant equations 3. The attempt at a solution The answer is " The tube must be inclined forwards from the vertical with respect to the path of the cart at an angle : theta= arctan(V(of cart)/V(of rain drop)) I had the hunch that it had to be leaned forward but I don't know how to arrive at this algebraic expression.