Chhattisgarh Board Solutions for Chapter: Work and Energy, Exercise 8: Exercise

On applying brakes of a car which is moving at a speed $v$, it stops after covering a distance $d$. Calculate, what will be the distance covered by the car after applying brakes if it was moving at a speed of $2v$.

A man holds a sack of rice on his head for $30$ minutes and gets tired. Has he done any work? Explain your answer with reasons.

On applying a force of $8$ Newton on a body, it moves in the direction of motion and displaces for $4$ meters. Calculate the work done.

A body of $10 \mathrm{kg}$ mass is raised against gravitational force of earth to a height of $10 \mathrm{m}$. How much work is done (in joules) in this case? ($g=10 \raisebox{1ex}{$\mathrm{m}$}\!\left/ \!\raisebox{-1ex}{${\mathrm{s}}^2$}\right.$)

Two bodies of masses $10 \mathrm{kg}$ and $15 \mathrm{kg}$ are raised to a height of $5 \mathrm{m}$ and $2 \mathrm{m}$ respectively above the surface of earth. Calculate the change in their potential energy in joules.

By using the information given in the figure, calculate the velocity of the ball at the position D. (use the law of conservation of mechanical energy).
 

On applying a force of $15 \mathrm{N} \text{for} 6 \sec$ a man displaces a box by $8 \mathrm{m}$. Calculate his power.

To change the energy of a body of $0.5 \mathrm{kg} \text{by} 1 \mathrm{J}$, we will have to raise it to what height? ($g = 10 \raisebox{1ex}{$\mathrm{m}$}\!\left/ \!\raisebox{-1ex}{${\mathrm{s}}^2$}\right.$).