A 70 lb weight stretches a spring 10 feet. The weight hangs vertically from the spring and a damping force numerically equal to 7 2?5 times the instantaneous velocity acts on the system. The weight is released from 5 feet above the equilibrium position with a downward velocity of 22 ft/s. (a) Determine the time (in seconds) at which the mass passes through the equilibrium position. (b) Find the time (in seconds) at which the mass attains its extreme displacement from the equilibrium position.