Sunil Batra Solutions for Chapter: Work and Energy, Exercise 3: Summative Assessment Some Solved CBSE Sample Questions

State the physical quantity which will be affected by changing the rate of doing work.

Differentiate between $\mathrm{kW}$ and $\mathrm{kWh}$.

A shot put player throws a shot put of mass $3 \mathrm{kg}$. If it crosses the top of a wall of $2 \mathrm{m}$ height at a speed of $4 \mathrm{m} {\mathrm{s}}^{-1}$, compute the total mechanical energy of shot put when it crosses the wall. (Take $g = 9.8 \mathrm{m}/{\mathrm{s}}^2$)

Compare the kinetic energies of two objects of masses $10 \mathrm{kg}$ and $50 \mathrm{kg}$ respectively but having same momentum.

In a tug of war, team $\mathrm{A}$ wins and team $\mathrm{B}$ loses. Which of these teams does (a) Positive work? (b) Negative work? Give reasons for your answer.

A motor pump rated $400 \mathrm{W}$ operates for $2$ minutes and $40$ seconds and in doing so, raises $200 \mathrm{kg}$ of water to the top of a building. If $\mathrm{g}=10 \mathrm{m} {\mathrm{s}}^{-2}$, Calculate the height of the building.

A force acting on a $10 \mathrm{kg}$ mass changes its velocity from $54 \mathrm{km}/\mathrm{h}$ to $90 \mathrm{km}/\mathrm{h}$. Calculate the work done by the force.

Five bulbs each rated $100 \mathrm{W}$ are used for $4$ hours, a heater rated $1500 \mathrm{W}$ is used for $2$ hours and an electric iron rated $1000 \mathrm{W}$ is used for $5$ hours. Calculate the total energy consumed by them in terms of commercial unit of energy. Convert the energy in joules.