Question

After a perfectly inelastic collision between two identical particles moving with same speed in different directions the speed of the particles becomes half the initial speed. The angle between velocities of the two before collision is –

• A. 60⁰
• B. 45⁰
• C. 120⁰
• D. 30⁰

Answer 1

Answer: (C)

120⁰

Answer 2

Conservation of linear momentum along x-axis.

mv cosa + mv cosa = 2m(v/2)

Ž cos a = $\frac{1}{2}$ Ž a = 60⁰

\ Angle between initial velocities = 120⁰