Question

A 105 kg football player runs at 8.5 m/s and plows into the back of an 85 kg referee running at 3.5 m/s on the field causing the referee to fly forward at 6.0 m/s.
What must the momentum of the football player be after the collision?

Answer 1

Answer:

680 Kg.m/s

Explanation:

Mass of player; m_p = 105 kg.

Speed of player before Collision; v_pi = 8.5 m/s

Mass of referee; m_r = 85 kg

Speed of referee before collision; v_ri = 3.5 m/s

Speed of referee after collision; v_rf = 6 m/s

From conservation of momentum,

Initial momentum = final momentum

Thus;

(m_p × v_pi) + (m_r × v_ri) = (m_p × v_pf) + (m_r × v_rf)

Where (m_p × v_pf) is the momentum of the player after collision.

Thus, Plugging in the relevant values, we have;

(105 × 8.5) + (85 × 3.5) = (m_p × v_pf) + (85 × 6)

(m_p × v_pf) = (105 × 8.5) + (85 × 3.5) - (85 × 6)

(m_p × v_pf) = 680 Kg.m/s