Dhiren M Doshi Solutions for Chapter: Work and Energy, Exercise 3: Check Your Progress

How fast should a man of $50 \mathrm{kg}$ run so that his kinetic energy is $625 \mathrm{J}$?

How is the kinetic energy of a moving body affected if its velocity is tripled?

How fast should a man of mass $60 \mathrm{kg}$ run so that his kinetic energy is $750 \mathrm{J}$?

A man drops a $10 \mathrm{kg}$ rock from the top of a $5 \mathrm{m}$ ladder. What is its speed just before it hits the ground? What is its K.E. when it reaches the ground? (take $g=10 \raisebox{1ex}{$\mathrm{m}$}\!\left/ \!\raisebox{-1ex}{${\mathrm{s}}^2$}\right.$)

What would have a greater effect on the kinetic energy of an object-doubling the mass or doubling the velocity?

A truck of mass $5000 \mathrm{kg}$ travelling at $40 \mathrm{m}/\mathrm{s}$ is brought to rest by applying brakes. The truck comes to rest after travelling $20 \mathrm{m}$ after the application of brakes. What is the kinetic energy of the truck?

A bullet of mass $50 \mathrm{g}$ is moved with a velocity of $500 \raisebox{1ex}{$\mathrm{m}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{s}$}\right.$. It penetrates $10 \mathrm{cm}$ into a still target and comes to rest. Calculate the kinetic energy possessed by the bullet.

A bullet of mass $50 \mathrm{g}$ is moved with a velocity of $500 \raisebox{1ex}{$\mathrm{m}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{s}$}\right.$. It penetrates $10 \mathrm{cm}$ into a still target and comes to rest. Calculate the average retarding force offered by the target.