Q. Water drops fall from a tap on the floor 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 the instant when first drop strikes the ground, will be

 1968  213 Motion in a Straight Line Report Error

Solution:

By the time 5 th water drop starts falling, the first water drop reaches the ground.
As

or
or
Hence, the interval of each water drop
When the 5 th drop starts its journey towards ground, the third drop travels in air for

Height (distance) covered by 3 rd drop in air is

So, third water drop will be at a height of