A ballistic pendulum is a device used to measure the velocity of a projectile€” for example, the muzzle velocity of a rifle bullet. The projectile is shot horizontally into, and becomes embedded in, the bob of a pendulum, as illustrated in Fig. 6.35. The pendulum swings upward to some height h, which is measured. The masses of the block and the bullet are known. Using the laws of momentum and energy, show that the initial velocity of the projectile is given by vo = [(m + M/m)]ˆš2gh.

m + M