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

C

Explanation

Kinetic energy `=(1)/(2) mv^(2)`
As both balls are falling through same height therefore they possess same velocity.
but `KE prop m " "` (If v = constant)
`therefore ((KE)_(1))/((KE)_(2))=(m_(1))/(m_(2))=(2)/(4)=(1)/(2)`