Question

Consider elastic collision of a particle of mass m moving with a velocity u with another particle of the same mass at rest. After the collision the projectile and the struck particle move in directions making angles theta₁ and theta₂ respectively with the initial direction of motion. The sum of the angles theta₁+theta₂ is:

• A. \(45^\circ\)
• B. \(90^\circ\)
• C. \(135^\circ\)
• D. 180^∘

Hint:

For elastic collision of equal masses: • One particle initially at rest • Velocities after collision are always perpendicular

Answer 1

The Correct Option is B

Step 1: In an elastic collision of two identical masses where one is initially at rest, both momentum and kinetic energy are conserved.
Step 2: It can be shown from vector momentum conservation that the velocities after collision are perpendicular.
Step 3: Hence, theta₁+theta₂ = 90^∘