Power and Energy Multiple Choice Questions(MCQs) & Answers

1 Which of the following device converts chemical energy in to electrical energy?

A Battery

B Loud Speaker

C Solar Cell

D Electric Motor

View Answer

Answer: Battery

2 Joule is a unit of:

A Work

B Power

C Momentum

D None of the above

View Answer

Answer: Work

3 When an object falls freely towards the ground, then its total energy:

A Increases

B Decreases

C Remains constant

D First increases then decreases

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Answer: Remains constant

4 What happens to the body on which work is done:

A It loses energy

B It gains energy

C No change in the energy

D First it loses then it gain

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Answer: It gains energy

5 What is the smallest unit of power?

A Watt

B Kilowatt

C Horse power

D Milliwatt

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Answer: Watt

6 What is the SI unit of Work?

A Joule

B erg

C g-cm

D Watt

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Answer: Joule

7 Which of the followings is an example of work done against force?

A Getting up with the stairs

B Get down with the stairs

C Walking on the flat ground

D Droping any object down from the top

View Answer

Answer: Getting up with the stairs

8 What is energy?

A energy is the rate of change of work done;

B It is the ability to do work;

C Both A and B;

D none of the above

View Answer

Answer: It is the ability to do work;

9 Potential energy = mass × ________ × height.

A Displacement

B Velocity

C Density

D Gravitational acceleration

View Answer

Answer: Gravitational acceleration

10 What is the formula of work done?

A Work done = force × displacement;

B Work done = force × velocity;

C Work done = pressure × displacement

D Work done = mass × acceleration;

View Answer

Answer: work done = force × displacement;

11 An object of mass 200 g moving with velocity 50 cm/s. What is its kinetic energy?

A 2.1 × 105 erg

B 2.0 × 105 erg

C 2.8 × 105 erg

D 2.5 × 105 erg

View Answer

Answer: 2.5 × 105 erg

12 A machine do a work of 100 joule in 20 second. What is its power?

A 120 watt

B 80 watt

C 5 watt

D 2000 watt

View Answer

Answer: 5 watt

13 Erg is related to –

A dyne-cm

B dyne/secon

C dyne-second

D dyne/cm

View Answer

Answer: dyne-cm

14 A particle is thrown upward with some kinetic energy. What happened to its kinetic energy at the highest point or height it reaches.

A Its kinetic energy is lost

B It’s all kinetic energy is absorbed by the air

C Its kinetic energy is converted to potential energy

D Its kinetic energy is remain same

View Answer

Answer: Its kinetic energy is converted to potential energy

15 A joule (J) is used as a unit of measurement for :

A Kinetic Energy

B Potential Energy

C Work done

D All of the above

View Answer

Answer: All of the above

16 When a spring is compressed or stretched beyond its natural position by applying some force, work is done on it. Its elastic potential energy

A increases

B Decreases

C Disappears

D Does not change

View Answer

Answer: increases

17 A car which is 8 times heavier than a motorcycle is moving at a speed which is just 1/2 the speed of motorcycle. . The amount of work done required to stop the car as compare to that of motorcycle, will be ?

A The same amount

B Twice as much

C Three times as much

D Four times as much

View Answer

Answer: Twice as much

18 Two objects A and B are moving with same momentum. Mass of object 'B' is greater then mass of object 'A'. Which of the two object will have higher kinetic energy?

A Object A

B Object B

C Both the objects will have same Kinetic Energy

D Object with greater mass will have higher kinetic energy

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