A girl standing on a stationary lift (open from above) throws a ball upwards with initial speed `50 m s^(-1)`. The time taken by the ball to return to her hands is (Take g = `10 m s^(-2)`)

Options

A. 5 s
B. 10 s
C. 15 s
D. 20 s

Answer

B

Explanation

Using, S = `ut + 1/2 at^(2)`
Here S = 0, u = `50 m s^(-1)`, a = - g = `- 10 m s^(-2)`
`therefore 0 = 50t + 1/2 xx (-10)t^(2) = 50t - 5t^(2) impliest = 10` s