Question

A 105 kg halfback runs north and is tackled by a 156 kg opponent running south at 6 m/s. The collision is perfectly inelastic. Just after the tackle, both players move at a velocity of 3 m/s north. Calculate the velocity (m/s) of the 105 kg player just before the tackle. Answer to one decimal place.

Answer 1

We can solve this problem using the conservation of momentum and the law of conservation of energy. Here's how:

Let v be the velocity of the 105 kg player just before the tackle. Then the velocity of the 156 kg player just before the tackle is -6 m/s, since he is running south. After the tackle, the two players move at a velocity of 3 m/s north, so we have:

Total momentum before = Total momentum after

(105 kg)(v) + (156 kg)(-6 m/s) = (105 kg + 156 kg)(3 m/s)

Simplifying and solving for v, we get:

v = (105 kg + 156 kg)(3 m/s) + (156 kg)(6 m/s) / 105 kg

v = 2.85 m/s

Therefore, the velocity of the 105 kg player just before the tackle was 2.85 m/s north.