Q. A point mass of 1 kg collides elastically with a stationary point mass of 5 kg. After their collision, the 1 kg mass reverses its direction and moves with a speed of$\ 2\ ms^{- 1}$. Which of the following statements(s) is/are correct for the system of these two masses?
A) Total momentum of the system is 3 $kg - ms^{- 1}$
B) Momentum of 5 kg mass after collision is 4 $kg - ms^{- 1}$
C) Kinetic energy of the centre of mass is 0.75 j
D) Total kinetic energy of the system is 4 j
Explanation
(d) As the speed of mass is uniform hence, net power will be zero.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.