An object is dropped is an unknown planet from height 50 m, it reaches the ground is 2 s. The acceleration due to gravity in this unknwon planet is

Options

A. `g = 20 ms^(-2)`
B. `g = 25 ms^(-2)`
C. `g = 15 ms^(-2)`
D. `g = 30 ms^(-2)`

Answer

B

Explanation

`s = ut + (1)/(2) at^(2) " " :. u = 0`
`50 = (1)/(2) g't^(2)`
`g' =(2xx50)/(t^(2))`
`g' = (2 xx 50)/(4) = 25 ms^(-2)`