Agent arlene devised the following method of measuring the muzzle velocity of a rifle. she fires a bullet into a 4.350-kg wooden block resting on a smooth surface, and attached to a spring of spring constant k = 145.0 n/m . the bullet, whose mass is 7.700 g , remains embedded in the wooden block. she measures the maximum distance that the block compresses the spring to be 9.460 cm. what is the speed v of the bullet?