Two balls are thrown simultaneously from ground with same velocity of `10 ms^(-1)` but different angles of projection with horizontally. Both balls fall at same distance `5sqrt(3)m` from point of projection. What is the time interval between balls striking the ground ?

Options

A. `(sqrt(3)-1)s`
B. `(sqrt(3)+1)s`
C. `sqrt(3)s`
D. 1s

Answer

A

Explanation

Given, `5sqrt(3) = ((10)^(2) sin 2 theta)/(g)` or `sin 2 theta = (sqrt(3))/(2)`
`:. 2 theta = 60^(@)` or `theta = 30^(@)`
Two different angles of projection are therefore `theta` and `90^(@) - theta` or `30^(@)` and `60^(@)`.
`:. T_(1) = (2u sin 30^(@))/(g) = 1s`
`:. T_(2) = (2u sin 60^(@))/(g) = sqrt(3)s`
`:. Deltat = T_(2) - T_(1) = (sqrt(3)-1)s`