Question

You are hired as ballistics expert and need to measure the muzzle speed of the bullet (with a mass, m = 20 g) for the gun. You fire a ballistic gun horizontally into a 2-kg ballistic pendulum (M = 2 kg) hanging at rest on a massless rod. After the bullet hits it and becomes embedded in it, the pendulum swings 0.5 m above its original height (h = 0.5 m).
Find the speed with which the bullet hits the block (muzzle velocity). Round the answer (use no digits after decimal place).
Hint: use both laws of conservation: for energy and momentum.