A projectile enters a resisting medium at x = 0 with an initial velocity v0 = 945 ft/s and travels 8.5 in. before coming to rest. Assume that the velocity of the projectile is defined by the relation v = v0 – kx, where v is expressed in ft/s and x is in feet. Determine: a. the initial acceleration of the projectile
b. the time required for the projectile to penetrate 3.9 in. into the resisting medium.