Question

Two bodies P and Q, of same masses m and 2m are moving with velocities 2 v and v respectively. Compare their
(i) Inertia, (ii) Momentum, and (iii) The force required to stop them in the same time.

Answer 1

Mass of P is m₁= m.
Velocity of P is v₁ =2 v
Mass of Q is m₂ = 2m
Velocity of Q is v₂ = v.
(i) inertia of P/inertia of Q = m₁/m₂ = 1/2.
So ratio of inertia of two bodies is 1:2.
(ii) Momentum of P/momentum of Q = m₁v₁/m₂v₂ = 1
So ratio of momentum of two bodies is 1:1.
(iii) As force required to stop them is equal to change in their momentum from moving to rest.
So ratio would be same as the ratio of their momentum i.e 1: 1.