Jatinder Singh Solutions for Chapter: Work, Energy and Power, Exercise 1: Expected Questions

A hydroelectric power station takes its water from a lake whose water level is $50 \mathrm{m}$ above the turbine. Assuming an overall efficiency of $40\%,$ calculate the mass of water which must flow through the turbine each second to produce power output of $1 \mathrm{MW}. (\mathrm{g}=10 {\mathrm{ms}}^{-2})$

A dog of mass $25 \mathrm{kg}$ running after a cat of mass $4 \mathrm{kg}$ possesses the same kinetic energy as that of the cat. Calculate the ratio of the velocities of the two.

A pump is used to lift $500 \mathrm{kg}$ of water from a depth of $80 \mathrm{m}$ in $10 \mathrm{s}.$ Calculate the work done by the pump. $(\mathrm{g} =10 {\mathrm{ms}}^{-2})$

A force is applied on a body of mass $20 \mathrm{kg}$moving with a velocity of $40 {\mathrm{ms}}^{-1}.$ The body attains a velocity of $50 {\mathrm{ms}}^{-1}$ in $2$seconds. Calculate work done by the body. 

A ball of mass $20 \mathrm{g}$falls from a height of $10 \mathrm{m}.$ It rebounds from the ground to $4 \mathrm{m}$. Find initial potential energy of ball.

A ball of mass $20 \mathrm{g}$falls from a height of $10 \mathrm{m}.$ It rebounds from the ground to $4 \mathrm{m}.$Find kinetic energy of the ball just before striking the ground.

A ball of mass $20 \mathrm{g}$falls from a height of $10 \mathrm{m}.$ It rebounds from the ground to $4 \mathrm{m}.$Find kinetic energy of the ball after striking the ground.

A ball of mass $20 \mathrm{g}$falls from a height of $10 \mathrm{m}.$ It rebounds from the ground to $4 \mathrm{m}.$Find loss in kinetic energy on striking the ground.