V K Sally and R Goel Solutions for Chapter: Motion, Exercise 12: EXERCISE

A photographer arranges to expose photographs of a ball describing motion under free fall, such that it is photographed on a vertical scaling starting from zero. He photographed the ball when it was at $76.05 \mathrm{m}$ and then when it was at $80 \mathrm{m}$. The time of exposure set on the camera is : (Take $\mathrm{g}=9.8 \mathrm{m}/{\mathrm{s}}^2$)

The water level in a well is at a depth of $125 \mathrm{m}$. If the acceleration due to gravity is $10 {\mathrm{ms}}^{-2}$ and a boy gently drops the stone, he hears the sound of splash in$5.35 \mathrm{s}$. The speed of sound is :

A freely falling stone covers half of its free fall from the top of a building in $0.5 \mathrm{s}$. The height of the building is:

A bullet fired on a wooden plank with a velocity of $10 \mathrm{m}/\mathrm{s}$ just penetrates through it. If the bullet penetrates $10$ such wooden planks, its velocity is :

A rain drop starts from a cloud at a height of $100\mathrm{m}$ and is acted upon a constant acceleration of $8\mathrm{m}/{\mathrm{s}}^2$ on account of friction of air. The velocity of raindrop on reaching ground is :

A car running at a speed $72 {\mathrm{kmh}}^{-1}$  is slowed down to $18{\mathrm{kmh}}^{-1}$ over a distance of $40 \mathrm{m}$. The retardation produced by its brakes is :

A car running at a speed $72 {\mathrm{kmh}}^{-1}$  is slowed down to $18{\mathrm{kmh}}^{-1}$ over a distance of $40 \mathrm{m}$. 

The time for which brakes are applied is :

An aeroplane on a runway, starts from rest and picks up a velocity of $180 {\mathrm{kmh}}^{-1 }$before taking off. If the length of runway covered is $1.5 \mathrm{km}$, the time in which it takes off is :