Agent Arlene devised the following method of measuring the muzzle velocity of a rifle. She fires a bullet into a 4.600-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 7.800g , 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?