Question

Three identical blocks A, B and C are placed on horizontal frictionless surface. The blocks B and C are at rest. But A is approaching towards B with a speed 10 m/s. The coefficient of restitution for all collisions is 0.5. The speed of the block C just after collision is –

• A. 5.6 m/s
• B. 6 m/s
• C. 8 m/s
• D. 10 m/s

Answer 1

Answer: (A)

5.6 m/s

Answer 2

Velocity of B after collision,

v_B = $\frac{m_{1}(1 + e)}{m_{1} + m_{2}}u_{1}$ = $\frac{(1 + 0.5)}{2} \times 10$= 7.5 m/s

Velocity of C after collision,

v_C = $\frac{m(1 + e)}{m + m}u_{1}$ = $\frac{(1 + 0.5)}{2}$×7.5 = 5.6 m/s