Water drops fall from a tap on the floor 5 m below at regular intervals of time, the first drop striking the floor when the fifth drop begins to fall. The height at which the third drop will be, from ground, at that instant when first drop strikes the ground, will be, (taking g = `10 ms^(-2))`

Options

A. 1.25 m
B. 2.15 m
C. 2.75
D. 3.75 m

Explanation

When the car accelerates,
`v=u+at`
`v=0+alphat_1 ( :'a=+alpha)`
`t_1=v/alpha .....(1)`
when car starts to retard,
`v=u+at`
`v=0+betat_2 ( :'a=-beta)`
`t_2=v/beta .....(2)`
Total time,
`t=t_1+t_2`
`t=v/alpha+v/beta`
`t=v(alpha+beta)/(alphabeta)`
`v=(alpha+beta)/(alphabeta)t`