A ball of mass`2 kg` and another of mass `4 kg` are dropped together from a `60` feet tall building . After a fall of `30` feet each towards earth , their respective kinetic energies will be the ratio of

Options

A. `sqrt2 : 1`
B. `1 : 4`
C. `1 :2`
D. `1 : sqrt2`

Answer

`(3)`

Explanation

Both balls attain same velocity v after falling through 30 feet height.
`therefore E_(1)/E_(2) = (1/2m_(1)v_(1)^(2))/(1/2m_(2)v_(2)^(2))= (2v^(2))/(4v^(2)) = 1/2 = 1:2`