Question

On a touchdown attempt, a 95.0 kg running back runs toward the end zone at 3.75 m/s. A 111-kg linebacker moving at 4.10 m/s meets the runner in a head-on collision. If the two players stick together. (a) What kind of collision is it and what quantity is conserved in this problem? (0.5 point) (b) Write down the appropriate conservation equation for the system. (0.5 points) (c) Find the final velocity vf. (both magnitude and direction) (0.5 points) (d) Calculate the initial kinetic energy of the two players. (0.5 points) (e) Calculate the final kinetic energy of the players. (1 points) (f) If the final speed of the two players is zero, should the speed of the running back be increased or decreased? (Show your work for full credit) (1 points) (g) Calculate the required speed (bonus). (1 points)

Answer 1

Given, m_1 = 95 kg, v_1 = 3 . 75 m/s m_2 = 111 kg, v_2 = 9 . 10 m/s (a) It is a perfectly inelastic collision because after collision both masses stick with each other . The quantity linear momentum remains conserved . (b) As both masses are moving in opposite direction . So, m_2 v_2 - m_1 v_1 = (m_1 + m_2) v_f (c) v_f = m_2 v_2 - m_1 v_1/m_1 + m_2 v_f = 111 kg times 4 . 1 m/s - 95 kg times 3 . 75 m/s/(111 + 95) kg v_f