Chapter 11.1, Problem 11.16P

A projectile enters a resisting medium at $x=0$ with an initial velocity $v_0=900$ ft/s and travels 4 in. before coming to rest. Assuming that the velocity of the projectile is defined by the relation $v=v_0-kx$ , 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.