Two bodies having equal masses are moving with uniform speeds of v and 2v respectively. Find the ratio of their kinetic energies.

Question

Philoid · Accepted Answer

Let the masses of the two bodies (m1) and (m2) be m kg

Let the velocity of the first body be v m/s

And the velocity of the second body be 2v m/s

Ratio of K.E = (KE) of body 1/ KE of body 2

= (1/2 mv²)/ (1/2 m (2v)²)

= v²/ (2v)² = (1)²/ (2)²

= 1:4 (K.E∝v²)

Hence, the ratio of their kinetic energies is 1:4