Question

High-speed stroboscopic photographs show that the head of a golf club of mass 200 grams is traveling at 55 m/s just before it strikes a 46-gram golf ball at rest on a tee. After the collision, the club head travels (in the same direction) at 40 m/s. Find the speed of the golf ball just after impact.

Answer 1

You need to use conservation of momentum here. Remember that momentum is mass times velocity.

Prior to impact, the golf club has a momentum of 0.200 kg * 55 m/s = 11.00 kg m/s.

The ball's not moving before impact, so it has a momentum of zero. Therefore the total momentum before impact will be 11.00 kg m/s. Conservation of momentum dictates the total momentum of the two objects after impact will also be 11.00 kg m/s.

We know the speed of the club after the impact, so the momentum of the club after impqact is 0.200 kg * 40 m/s =8 kg m/s.

So the momentum of the ball must be 11.00 kg m/s - 8 kg m/s = 3 kg m/s, and dividing by the mass of the ball (0.046 kg) gives the speed of the ball, 65.217 m/s