Question

A particle (𝑝1) of mass 𝑚 moving with speed 𝑣 collides with a stationary identical particle (𝑝2). The particles bounce off each other elastically with 𝑝1 getting deflected by an angle 𝜃 = 30° from its original direction. Then, which of the following statement(s) is/are true after the collision?

• A. Speed of 𝑝1 is $\frac{\sqrt3}{2}$ V
• B. Kinetic energy of 𝑝2 is 25% of the total energy
• C. Angle between the directions of motion of the two particles is 90°
• D. The kinetic energy of the centre of mass of 𝑝1 and 𝑝2 decreases

Answer 1

Answer: (A), (B), (C)

Speed of 𝑝1 is $\frac{\sqrt3}{2}$ V

Answer 2

The correct options are: A, B and C