Physics Circle home Student Login

Home›Chapters›Work, Energy and Power PYQs›Collisions›Question 10

NEET 2015 (AIPMT) · Collisions

Collisions question from NEET 2015 (AIPMT)

Q10NEET 2015 · AIPMTMedium

Collisions

On a frictionless surface, a block of mass M moving at speed v collides elastically with another block of same mass M which is initially at rest. After collision the first block moves at an angle θ\theta to its initial direction and has a speed v3.\frac{v}{3}. The second block's speed after the collision is

Show answer and solution

Answer: (c)

  1. Elastic collision: kinetic energy is conserved, 12Mv2=12M(v3)2+12Mv22\frac{1}{2}Mv^2 = \frac{1}{2}M\left(\frac{v}{3}\right)^2 + \frac{1}{2}Mv_2^2
  2. v22=v2−v29=89v2v_2^2 = v^2 - \frac{v^2}{9} = \frac{8}{9}v^2
  3. v2=223vv_2 = \frac{2\sqrt{2}}{3}v
  4. So the answer is (c).
Report a mistake

More questions on Collisions