Two blocks are hung by a string draped over a pulley, a 1.3-kg block on the left and a 3.0-kg block on the right. The two blocks start out at rest and at the same height. Required:
a. What is the change in the gravitational potential energy of the system of blocks and Earth when the 2.9-kg block has dropped 0.61 m?
b. What is the change in the kinetic energy of the system between release and this instant?
c. What is the velocity of the 1.3-kg block at this instant?