Work, Energy and Power MCQs 2026

Friction is an example of a

1. AConservative force✓
2. BNon-conservative force✓
3. CCentral force✓
4. DGravitational force✓

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

1. AMomentum✓
2. BPotential energy✓
3. CMass✓
4. DKinetic energy✓

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

1. AFriction✓
2. BGravity✓
3. CInertia✓
4. DMomentum conservation✓

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

1. AFraction only✓
2. BRatio of masses✓
3. CPercentage✓
4. DDifference of energies✓

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

1. Akx✓
2. B(1/2)kx^2✓
3. Ckx^2✓
4. D(1/2)kx✓

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

1. Amg/h✓
2. Bmh/g✓
3. C(1/2)mgh✓
4. Dmgh✓

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

1. A10 joules✓
2. B50 joules✓
3. C100 joules✓
4. D25 joules✓

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

1. A9 joules✓
2. B6 joules✓
3. C18 joules✓
4. D3 joules✓

Power can also be expressed as the product of force and

1. ADisplacement✓
2. BVelocity✓
3. CAcceleration✓
4. DTime squared✓

One horsepower is approximately equal to

1. A100 watts✓
2. B550 watts✓
3. C1000 watts✓
4. D746 watts✓

The SI unit of power is the

1. AJoule✓
2. BNewton✓
3. CWatt✓
4. DPascal✓

Power is defined as the rate at which

1. AWork is done✓
2. BMass changes✓
3. CVelocity changes✓
4. DForce is applied✓

One calorie of heat energy is approximately equal to

1. A1 joule✓
2. B4.2 joules✓
3. C42 joules✓
4. D0.24 joules✓

The SI unit of energy is the same as that of

1. APower✓
2. BForce✓
3. CWork✓
4. DMomentum✓

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. Bmgh✓
3. Cmgh^2✓
4. D(1/2)mgh✓

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

1. A(1/2)mv^2✓
2. Bmv^2✓
3. Cmgh✓
4. D(1/2)mv✓

The two main forms of mechanical energy are

1. AHeat and light energy✓
2. BChemical and nuclear energy✓
3. CSound and electrical energy✓
4. DKinetic and potential energy✓

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

1. AZero✓
2. BMaximum✓
3. CNegative✓
4. DEqual to the force✓

The SI unit of work is the

1. AWatt✓
2. BJoule✓
3. CNewton✓
4. DPascal✓

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

1. AMass of the body✓
2. BTime taken✓
3. CAcceleration produced✓
4. DCosine of the angle between force and displacement✓

Energy is generally defined as the capacity of a body to

1. ARemain at rest✓
2. BDo work✓
3. CResist motion✓
4. DExert torque✓

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

1. ATransformed from one form to another✓
2. BDecreased✓
3. CMeasured✓
4. DIncreased✓

Electrical appliances are commercially rated in watts mainly to indicate their

1. ATotal stored energy✓
2. BTotal mass✓
3. CRate of energy consumption✓
4. DTotal voltage✓

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

1. AElectrical energy✓
2. BChemical energy✓
3. CLight energy✓
4. DHeat energy✓

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

1. ANuclear energy✓
2. BChemical energy✓
3. CElastic energy✓
4. DSolar energy✓

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

1. ANuclear energy✓
2. BChemical energy✓
3. CMechanical energy✓
4. DThermal energy✓

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

1. A100 kWh✓
2. B5 kWh✓
3. C0.5 kWh✓
4. D50 kWh✓

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

1. AJoules only✓
2. BWatts✓
3. CNewtons✓
4. DKilocalories✓

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

1. AGround level✓
2. BCenter of the Earth✓
3. CTop of a building✓
4. DSurface of the moon✓

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

1. A50 joules✓
2. B25 joules✓
3. C12.5 joules✓
4. D5 joules✓

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

1. AChemical energy✓
2. BSound energy✓
3. CKinetic energy✓
4. DHeat energy✓

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

1. AHeat and light energy✓
2. BChemical and nuclear energy✓
3. CSound and electrical energy✓
4. DKinetic and potential energy✓

One megawatt is equal to

1. A10^6 watts✓
2. B10^3 watts✓
3. C10^9 watts✓
4. D10^2 watts✓

One kilowatt is equal to

1. A100 watts✓
2. B1000 watts✓
3. C10 watts✓
4. D10000 watts✓

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

1. A1 joule per hour✓
2. B1 joule per minute✓
3. C1 joule per second✓
4. D1 calorie per second✓

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

1. A50 percent✓
2. B75 percent✓
3. C90 percent✓
4. D100 percent✓

Solar panels convert light energy directly into

1. AElectrical energy✓
2. BMechanical energy✓
3. CChemical energy✓
4. DSound energy✓

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

1. AChemical energy✓
2. BElectrical energy✓
3. CNuclear energy✓
4. DSound energy✓

The energy stored in a stretched or compressed spring is called

1. AKinetic energy✓
2. BGravitational potential energy✓
3. CElastic potential energy✓
4. DChemical energy✓

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

1. AP = F/v✓
2. BP = F + v✓
3. CP = v/F✓
4. DP = Fv✓

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

1. ADisplacement is perpendicular to the gravitational force✓
2. BForce of gravity is zero✓
3. CLoad has no mass✓
4. DVelocity is constant✓

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

1. AZero✓
2. BNegative✓
3. CPositive✓
4. DUndefined✓

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

1. AZero✓
2. BPositive✓
3. CMaximum✓
4. DNegative✓

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

1. AOpposite direction to the force✓
2. BDirection of the force✓
3. CDirection perpendicular to the force✓
4. DDirection at 45 degrees to the force✓

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

1. AJoule✓
2. BWatt✓
3. CKilowatt-hour✓
4. DNewton-metre✓

One kilowatt-hour of energy is equal to

1. A3.6 x 10^3 joules✓
2. B3.6 x 10^4 joules✓
3. C3.6 x 10^5 joules✓
4. D3.6 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. A500 watts✓
2. B1000 watts✓
3. C50 watts✓
4. D5000 watts✓

Coal and petroleum are examples of

1. ARenewable energy sources✓
2. BNuclear energy sources✓
3. CNon-renewable energy sources✓
4. DSolar energy sources✓

Solar and wind energy are examples of

1. ANon-renewable energy sources✓
2. BNuclear energy sources✓
3. CChemical energy sources✓
4. DRenewable energy sources✓

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

1. AFrictional force✓
2. BNon-conservative force✓
3. CConservative force✓
4. DCentripetal force✓