Question

A 92.0 kg football player at 6.50 m/s North collides with an 85.0 kg football player running at 6.00 m/s south. The 92.0 kg football player continues moving at a velocity of 2.00 m/s after the collision. What is the velocity of the 85.0 kg football player after the collision?

Answer 1

-1.13 m/s

Explanation:

Parameters given:

Mass of first footballer, M = 92 kg

Initial velocity of first footballer, U = 6.5 m/s (taking North to be the +ve y axis)

Mass of second footballer, m = 85 kg

Initial velocity of second footballer, u = -6.0 m/s (taking South to be the -ve y axis)

Final velocity of first footballer, V = 2.0 m/s

We need to find the final velocity of the second football (v)

Applying the principle of conservation of momentum, we have that, in a system:

Total Initial Momentum = Total Final Momentum

(M * U) + (m * u) = (M * V) + (m * v)

(92 * 6.5) + (85 * -6) = (92 * 2) + (85 * v)

598 - 510 = 184 + 85v

88 = 184 + 85v

88 - 184 = 85v

-96 = 85v

=> v = -96 / 85

v = -1.13 m/s

The final velocity of the 85 kg player is -1.13 m/s i.e 1.13 m/s South