Water droplets are coming from an open tap at particular rate. The spacing between a droplet observed at $4^{{th}}\;second$ after its fall to the next droplet is $34.3 \,{m}$. At what rate the droplets are coming from the tap ? (Take $g=9.8\, {m} / {s}^{2}$)

Reaction time : When a situation demands our immediate action, it takes some time before we really respond. Reaction time is the time a person takes to observe, think and act. For example, if a person is driving and suddenly a boy appears on the road, then the time elapsed before he slams the brakes of the car is the reaction time. Reaction time depends on complexity of the situation and on an individual.

You can measure your reaction time by a simple experiment. Take a ruler and ask your friend to drop it vertically through the gap between your thumb and forefinger . After you catch it, find the distance $d$ travelled by the ruler. In a particular case, $d$ was found to be $21.0\; cm$. Estimate reaction time in second.

Three different objects of masses ${m_1},{m_2}$ and ${m_3}$ are allowed to fall from rest and from the same point $‘O’$ along three different frictionless paths. The speeds of the three objects, on reaching the ground, will be in the ratio of

A stone is allowed to fall from the top of a tower $100\,\,metre$  high and at the same time another stone is projected vertically upwards from the ground with a velocity of $25\,\,ms^{-1}.$  The two stones will meet after………$s$