NEETPhysicsCenter of Mass, Momentum and Collision
A ball of mass m moving with speed v strikes a rigid surface. Match the collision scenarios in List-I with the magnitude of impulse imparted to the ball in List-II. (A) Strikes normally and rebounds perfectly (I) mv (B) Strikes at 30^ to the normal and rebounds perfectly (II) 2mv (C) Strikes at 60^ to the normal and rebounds perfectly (III) 3 mv (D) Strikes at 45^ to the normal and rebounds perfectly (IV) 2 mv Choose
Options
- A(A)-(II), (B)-(I), (C)-(III), (D)-(IV)
- B(A)-(II), (B)-(IV), (C)-(III), (D)-(I)
- C(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
- D(A)-(I), (B)-(III), (C)-(II), (D)-(IV)
Correct answer
C. (A)-(II), (B)-(III), (C)-(I), (D)-(IV)
Step-by-step solution
When a ball strikes a rigid surface at an angle with the normal and rebounds perfectly (elastically) with the same speed v at the same angle, the change in momentum is only along the normal direction. The magnitude of impulse imparted is given by: J = | p| = 2mv (A) Strikes normally ( = 0^ ): J = 2mv (0^ ) = 2mv (Matches II) (B) Strikes at 30^ to the normal ( = 30^ ): J = 2mv (30^ ) = 2mv ( 3 2 ) = 3 mv (Matches III) (C) Strikes at 60^ to the normal ( = 60^ ): J = 2mv (60^ ) = 2mv ( 1 2 ) = mv (Matches I) (D) Strik