Lakhmir Singh and Manjit Kaur Solutions for Chapter: Work and Energy, Exercise 12: Short Answer Type Questions

Find the momentum of a body of mass $100 \mathrm{g}$ having a kinetic energy of $20 \mathrm{J}$.

A body of $2 \mathrm{kg}$ falls from rest. What will be its kinetic energy during the fall at the end of $2 \mathrm{s} ?$ (Assume $g=10 \mathrm{m}/{\mathrm{s}}^2$) 

A body of mass $100 \mathrm{k}\mathrm{g}$ is lifted by $10 \mathrm{m}$. Find potential energy of the body at that height. (value of $\mathrm{g}=10 \raisebox{1ex}{$\mathrm{m}$}\!\left/ \!\raisebox{-1ex}{${\mathrm{s}}^2$}\right.$)

When is the work done by a force on a body : (a) positive, (b) negative, and (c) zero?

Give one example each of a body possessing: (i) kinetic energy, and (ii) potential energy.

A boy weighing $40 \mathrm{kg}$ makes a high jump of $1.5 \mathrm{m}$. What is his kinetic energy at the highest point? (take, $g=10 m/s^2$)

A weightlifter is lifting weights of mass $200 \mathrm{k}\mathrm{g}$ up to a height of $2 \text{metres}$. If $\mathrm{g}=9.8 \mathrm{m} {\mathrm{s}}^{-2}$, calculate the potential energy acquired by the weights.

A weightlifter is lifting weights of mass $200 \mathrm{k}\mathrm{g}$ up to a height of $2 \text{metres}$. If $\mathrm{g}=9.8 \mathrm{m}{\mathrm{s}}^{-2}$, calculate the work done by the weightlifter.