The spring is compressed an amount δ = 80 mm and the system is released from rest. Deter...

The spring is compressed an amount δ = 80 mm and the system is released from rest. Determine the power supplied by the spring to the 4-kg cart (a) just after release, (b) as the cart passes the position for which the spring is compressed an amount δ/2, and (c) as the cart passes the equilibrium position.