Question

Two balls A and B of masses m and 2m are in motion with velocities 2v and v respectively. Compare : (i) their inertia, (ii) their momentum, and (iii) the force needed to stop them in the same time.

Answer 1

(i) Inertia
We know that mass is a measure of inertia. As ball B has a larger mass than ball A, its inertia will be more.

(ii) Momentum
Momentum of ball A = m $\times$ 2v = 2mv
Momentum of ball B = 2m $\times$ v = 2mv
Hence, both have the same momentum.

(iii) Force needed to stop them in the same time
The force needed to stop a body in a given time is proportional to its momentum. As momentum is same for both the bodies, the force required is also same.