A moving body strikes an identical stationary body obliquely in a perfectly elastic collision. One outgoing body makes 15° with the original direction; the other makes N×15° with it. Find N.
Physics · Mixed Chapter
JEE Main Practice

Question

A moving body strikes an identical stationary body obliquely in a perfectly elastic collision. One outgoing body makes 15° with the original direction; the other makes N×15° with it. Find N.

G1 Physics · Accepted Answer

Step 1: For an elastic collision of equal masses when one is initially at rest, outgoing velocity vectors are mutually perpendicular. Step 2: If one makes 15° with the initial direction, the other makes 90°−15°=75°. Step 3: N×15°=75° ⇒N=5.