1. The problem statement, all variables and given/known data In the arrangement shown in Fig. 1.18(see attachment) the mass of ball 1 is η=1.8 times as great as that of rod 2. The length of the latter is l = 100 cm. The masses of the pulleys and the threads, as well as the friction, are negligible. The ball is set on the same level as the lower end of the rod and then released. How soon will the ball be opposite the upper end of the rod? 2. Relevant equations 3. The attempt at a solution Well, i couldn't solve it so i had to peep into the solution. Here's the solution: http://irodovsolutionsmechanics.blogspot.in/2007/08/irodov-problem-175.html I don't quite understand the solution. It says that the ball goes up but that doesn't make sense to me. It is mentioned in the question that ball is heavier than the rod. The ball should move down as it is heavier. Please someone explain where i am going wrong. Thanks!