1. The problem statement, all variables and given/known data Two equal masses hang on either side of a pulley at the same height from the ground. The mass on the right is given a horizontal speed, then after some time-- (A) The mass on the left will be nearer to ground. (B) The mass on the right will be nearer to ground. (C) Both the masses will be at equal distance from the ground. (D) Nothing can be said regarding their positions. 2. Relevant equations 3. The attempt at a solution Just thinking visually, I feel that as the mass on the right moves with a horizontal velocity, the left mass will lift up. So, answer is B, which is in fact the right answer. But the masses also feel tension and I just think there must be a more concrete explanation.