A 75-kg man and 40-kg girl sit on the seesaw, which has negligible mass. At the instant

Question:

A 75-kg man and 40-kg girl sit on the seesaw, which has negligible mass. At the instant the man lifts his feet from the ground, determine their acceleration if each sits upright, i.e., they do not rotate. The centers of mass of the man and girl are at G_m and G_g, respectively.