Work, Energy and Power MCQs 2026

A 100-watt bulb used continuously for 5 hours consumes electrical energy of

1. A 100 kWh ✓
2. B 5 kWh ✓
3. C 0.5 kWh ✓
4. D 50 kWh ✓

The energy stored in fuels and food due to their chemical composition is called

1. A Nuclear energy ✓
2. B Chemical energy ✓
3. C Mechanical energy ✓
4. D Thermal energy ✓

The energy released from the fission or fusion of atomic nuclei is called

1. A Nuclear energy ✓
2. B Chemical energy ✓
3. C Elastic energy ✓
4. D Solar energy ✓

In machines, the energy lost to friction is mainly dissipated in the form of

1. A Electrical energy ✓
2. B Chemical energy ✓
3. C Light energy ✓
4. D Heat energy ✓

Electrical appliances are commercially rated in watts mainly to indicate their

1. A Total stored energy ✓
2. B Total mass ✓
3. C Rate of energy consumption ✓
4. D Total voltage ✓

According to the law of conservation of energy, energy can neither be created nor destroyed but can only be

1. A Transformed from one form to another ✓
2. B Decreased ✓
3. C Measured ✓
4. D Increased ✓

Energy is generally defined as the capacity of a body to

1. A Remain at rest ✓
2. B Do work ✓
3. C Resist motion ✓
4. D Exert torque ✓

Work done by a force is defined as the product of force, displacement, and the

1. A Mass of the body ✓
2. B Time taken ✓
3. C Acceleration produced ✓
4. D Cosine of the angle between force and displacement ✓

The SI unit of work is the

1. A Watt ✓
2. B Joule ✓
3. C Newton ✓
4. D Pascal ✓

If a force acts perpendicular to the direction of displacement, the work done by that force is

1. A Zero ✓
2. B Maximum ✓
3. C Negative ✓
4. D Equal to the force ✓

The two main forms of mechanical energy are

1. A Heat and light energy ✓
2. B Chemical and nuclear energy ✓
3. C Sound and electrical energy ✓
4. D Kinetic and potential energy ✓

The kinetic energy of a body of mass m moving with velocity v is given by

1. A (1/2)mv^2 ✓
2. B mv^2 ✓
3. C mgh ✓
4. D (1/2)mv ✓

The gravitational potential energy of a body of mass m at height h above the ground is given by

1. A (1/2)mv^2 ✓
2. B mgh ✓
3. C mgh^2 ✓
4. D (1/2)mgh ✓

The SI unit of energy is the same as that of

1. A Power ✓
2. B Force ✓
3. C Work ✓
4. D Momentum ✓

One calorie of heat energy is approximately equal to

1. A 1 joule ✓
2. B 4.2 joules ✓
3. C 42 joules ✓
4. D 0.24 joules ✓

Power is defined as the rate at which

1. A Work is done ✓
2. B Mass changes ✓
3. C Velocity changes ✓
4. D Force is applied ✓

The SI unit of power is the

1. A Joule ✓
2. B Newton ✓
3. C Watt ✓
4. D Pascal ✓

One horsepower is approximately equal to

1. A 100 watts ✓
2. B 550 watts ✓
3. C 1000 watts ✓
4. D 746 watts ✓

Power can also be expressed as the product of force and

1. A Displacement ✓
2. B Velocity ✓
3. C Acceleration ✓
4. D Time squared ✓

A body of mass 2 kg moving with a velocity of 3 m/s has a kinetic energy of

1. A 9 joules ✓
2. B 6 joules ✓
3. C 18 joules ✓
4. D 3 joules ✓

Taking g = 10 m/s^2, the potential energy of a 5 kg mass raised to a height of 2 metres is

1. A 10 joules ✓
2. B 50 joules ✓
3. C 100 joules ✓
4. D 25 joules ✓

The work done by gravity when a body of mass m falls freely through a height h is given by

1. A mg/h ✓
2. B mh/g ✓
3. C (1/2)mgh ✓
4. D mgh ✓

The elastic potential energy stored in a spring stretched by x with spring constant k is given by

1. A kx ✓
2. B (1/2)kx^2 ✓
3. C kx^2 ✓
4. D (1/2)kx ✓

For a freely falling body neglecting air resistance, as it falls its potential energy is converted into

1. A Chemical energy ✓
2. B Sound energy ✓
3. C Kinetic energy ✓
4. D Heat energy ✓

A force of 10 newtons acting at an angle of 60 degrees to a displacement of 5 metres does work equal to

1. A 50 joules ✓
2. B 25 joules ✓
3. C 12.5 joules ✓
4. D 5 joules ✓

Gravitational potential energy is usually measured relative to a chosen reference level, which is often taken as the

1. A Ground level ✓
2. B Center of the Earth ✓
3. C Top of a building ✓
4. D Surface of the moon ✓

The energy the human body obtains from food is commonly measured in units of

1. A Joules only ✓
2. B Watts ✓
3. C Newtons ✓
4. D Kilocalories ✓

The efficiency of a machine is defined as the ratio of output energy to input energy, usually expressed as a

1. A Fraction only ✓
2. B Ratio of masses ✓
3. C Percentage ✓
4. D Difference of energies ✓

When friction acts opposite to the direction of motion of a body, the work done by friction is

1. A Zero ✓
2. B Positive ✓
3. C Maximum ✓
4. D Negative ✓

When the force applied on a body acts in the same direction as its displacement, the work done is

1. A Zero ✓
2. B Negative ✓
3. C Positive ✓
4. D Undefined ✓

A person carrying a load horizontally at constant height does zero work against gravity because the

1. A Displacement is perpendicular to the gravitational force ✓
2. B Force of gravity is zero ✓
3. C Load has no mass ✓
4. D Velocity is constant ✓

The relation connecting power P, force F and velocity v for a body moving at constant velocity is

1. A P = F/v ✓
2. B P = F + v ✓
3. C P = v/F ✓
4. D P = Fv ✓

The energy stored in a stretched or compressed spring is called

1. A Kinetic energy ✓
2. B Gravitational potential energy ✓
3. C Elastic potential energy ✓
4. D Chemical energy ✓

In a hydroelectric power plant, the potential energy of stored water is mainly converted into

1. A Chemical energy ✓
2. B Electrical energy ✓
3. C Nuclear energy ✓
4. D Sound energy ✓

Solar panels convert light energy directly into

1. A Electrical energy ✓
2. B Mechanical energy ✓
3. C Chemical energy ✓
4. D Sound energy ✓

An ideal machine with no friction or energy losses would have an efficiency of

1. A 50 percent ✓
2. B 75 percent ✓
3. C 90 percent ✓
4. D 100 percent ✓

By definition, one watt is equal to an energy transfer rate of

1. A 1 joule per hour ✓
2. B 1 joule per minute ✓
3. C 1 joule per second ✓
4. D 1 calorie per second ✓

One kilowatt is equal to

1. A 100 watts ✓
2. B 1000 watts ✓
3. C 10 watts ✓
4. D 10000 watts ✓

One megawatt is equal to

1. A 10^6 watts ✓
2. B 10^3 watts ✓
3. C 10^9 watts ✓
4. D 10^2 watts ✓

The total mechanical energy of a body is the sum of its

1. A Heat and light energy ✓
2. B Chemical and nuclear energy ✓
3. C Sound and electrical energy ✓
4. D Kinetic and potential energy ✓

One joule of work is done when a force of 1 newton displaces a body through 1 metre in the

1. A Opposite direction to the force ✓
2. B Direction of the force ✓
3. C Direction perpendicular to the force ✓
4. D Direction at 45 degrees to the force ✓

The commercial unit of electrical energy used for billing purposes is the

1. A Joule ✓
2. B Watt ✓
3. C Kilowatt-hour ✓
4. D Newton-metre ✓

One kilowatt-hour of energy is equal to

1. A 3.6 x 10^3 joules ✓
2. B 3.6 x 10^4 joules ✓
3. C 3.6 x 10^5 joules ✓
4. D 3.6 x 10^6 joules ✓

A pump that lifts 100 kg of water through a height of 5 metres in 10 seconds does work against gravity at a power (taking g = 10 m/s^2) of

1. A 500 watts ✓
2. B 1000 watts ✓
3. C 50 watts ✓
4. D 5000 watts ✓

Coal and petroleum are examples of

1. A Renewable energy sources ✓
2. B Nuclear energy sources ✓
3. C Non-renewable energy sources ✓
4. D Solar energy sources ✓

Solar and wind energy are examples of

1. A Non-renewable energy sources ✓
2. B Nuclear energy sources ✓
3. C Chemical energy sources ✓
4. D Renewable energy sources ✓

Friction is an example of a

1. A Conservative force ✓
2. B Non-conservative force ✓
3. C Central force ✓
4. D Gravitational force ✓

A force whose work done is independent of the path taken and depends only on initial and final positions is called a

1. A Frictional force ✓
2. B Non-conservative force ✓
3. C Conservative force ✓
4. D Centripetal force ✓

The work-energy theorem states that the net work done on a body equals the change in its

1. A Momentum ✓
2. B Potential energy ✓
3. C Mass ✓
4. D Kinetic energy ✓

In practical machines, the efficiency is always less than 100 percent mainly due to energy losses caused by

1. A Friction ✓
2. B Gravity ✓
3. C Inertia ✓
4. D Momentum conservation ✓