Question

Two balls are colliding obliquely. Assume that the balls are smooth and all other external forces are absent then,

• A. The component of the momentum of each ball separately perpendicular to the line of impact is conserved.
• B. The component of the momentum of system perpendicular to the line of impact is conserved.
• C. Both (a) and (b) are correct.
• D. Both (a) and (b) are incorrect.

Answer 1

The correct option is C Both (a) and (b) are correct.

Two balls having smooth surface are colliding obliquely. There are no net external force perpendicular to the line of impact.

As we know, no component of impulse acts perpendicular to the line of impact.
Hence the velocity of the balls perpendicular to the line of impact remains same and thus component of momentum of each ball separately perpendicular to the line of impact is conserved.

We can also say that, the component of the momentum of system perpendicular to the line of impact is conserved.