2. A 1.2 kg cart slides eastward down a frictionless ramp from a height of 1.8 m and then onto a horizontal surface where it has a head-on elastic collision with a stationary 2.0 kg cart cushioned by an ideal Hooke's law spring. The maximum compression of the spring during the collision is 2.0 cm. a) Determine the spring constant. b) Calculate the velocity of each cart just after the collision. c) After the collision, the 1.2 kg cart rebounds up the ramp. Determine the maximum height reached by the cart.