Question

The mass of a ball A is double the mass of another ball B. The ball A moves at half the speed of the ball B . Calculate the ratio of the kinetic energy of A to the kinetic energy of B.

Answer 1

Since KE = 1/2mv^2

Therefore, KE of ball A = 1/2*(2m)*(v)^2 -----(1)

And KE of ball B = 1/2*(m) *(2v)^2 ----(2)

Now, ratio of KE's of both balls,

=> (KE of ball A)/(KE of ball B)

=> [1/2*(2m)*(v)^2]/[1/2*(m)*(2v)^2]

=> 2/4

=> 1/2

Therefore, ratio of KE of ball A to ball B is 1 : 2