Question

Two particles moving initially in the same direction undergo a one-dimensional, elastic collision. Their relative velocities before and after the collision are Vector v₁ and Vector v₂. Which of the following is not correct?

(a) | Vector v₁ | = | Vector v₂ |

(b) Vector v₁ = - Vector v₂ only if the two are of equal mass.

(c) Vector v₁ . Vector v₂ = - | Vector v₁ |²

(d) | Vector v₂ . Vector v₁ | = Vectoe v₂|²

Answer 1

Correct Answer is: (b) Vector v₁ = - Vector v₂ only if the two are of equal mass.

For a head-on elastic collision,

relative velocity after collision

= - relative velocity before collision.

This is independent of the masses of the particles.