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.

A ball is released from a height $h$. If $t_{1}$ and $t_{2}$ be the time required to complete first half and second half of the distance respectively. Then, choose the correct relation between $t_{1}$ and $t_{2}$.

A body falls from rest, its velocity at the end of first second is……… $ft/\sec $ $(g = 32ft/\sec )$

A frictionless wire $AB$ is fixed on a sphere of radius $R$. A very small spherical ball slips on this wire. The time taken by this ball to slip from $A $ to $B$ is

A particle is dropped vertically from rest from a height. The time taken by it to fall through successive distances of $1\, m$ each will then be