1. A 6,100-kg truck runs into the rear of a 1,000-kg car that was stationary. The truck and car are locked together after the collision and move with speed 5 m/s. Compute how much kinetic energy was "lost" in this inelastic collision.

2. A32kg child uses a pogo stick to bounce up and down. The spring constant,k, of the toy equals8,900N/m.(a)By how much would the spring be compressed by the child if she simply balanced herself vertically on the pedals of the stick? (Give your answer in cm.) cm(b)How much energy (in J) is stored in the spring under this circumstance?