A ball of mass moving with velocity makes an oblique elastic collision with a stationary ball of mass 2 The angle of divergence between the balls after collision in ground frame, if the ball of mass turns by an angle of in centre of mass frame is |
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a) |
b) |
c) |
d) |

A ball of mass moving with velocity makes an oblique elastic collision with a stationary ball of mass 2 The angle of divergence between the balls after collision in ground frame, if the ball of mass turns by an angle of in centre of mass frame is |
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a) |
b) |
c) |
d) |

1 Answer - 5876 Votes

3537

**(d)**

Let us solve this question in frame. As the collision is elastic, the magnitude of momenta of all balls remains same after collision in this frame

Velocity of frame w.r.t. ground frame is

The momentum diagram in frame is drawn as shown in fig.

Now, velocity of after colision in frame is while that of is along and , respectively. Let and be the velocities of and , respectively after collision in ground frame, then velocity vector diagrams can be drawn as shown

Using trigonometry, from upper triangle

From lower triangle:

So, angle of divergence is

**Alternative method **Write down conservation of momentum equations, coefficient of restitution equation, energy conservation and use the given conditions