Well structured WBBSE Class 9 Physical Science MCQ Questions Chapter 5 Work, Power and Energy can serve as a valuable review tool before exams.

## Work, Power and Energy Class 9 WBBSE MCQ Questions

Multiple Choice Questions :

Question 1.

What type of energy a raised hammer possesses ?

(i) Kinetic energy

(ii) Potential energy

(iii) Gravitational energy

Answer:

Potential energy

Question 2.

What is the absolute unit of force in SI system ?

(i) 1 kg-m

(ii) 1 joule

(iii) 1 erg

Answer:

1 Joule

Question 3.

What is the relation between power and force ?

(i) power = force × velocity

(ii) velocity = force × power

(iii) force = power × velocity

Answer:

power = force × velocity.

Question 4.

What is the amount of work performed by a person on the weight w that he carries and moves horizontally through a distance d ?

(i) No work is done

(ii) Work done = w × d

(iii) work done = w ÷ d

Answer:

No work is done

Question 5.

The dimension of energy is :

(i) [M L^{2} T^{-2}]

(ii) [M^{2} L^{2} T^{3}]

(iii) [M L^{2} T^{3}]

(iv) [M L^{3} T^{2}]

Answer:

ML^{2} T-^{2}

Question 6.

1 Horse power = ______.

(i) 7.46 watt

(ii) 74.6 watt

(iii) 746 watt

(iv) 7460 watt

Answer:

746 watt

Question 7.

All energies are transformed ultimately into :

(i) heat energy

(ii) kinetic energy

(iii) sound energy

(iv) electric energy

Answer:

Heat energy

Question 8.

Which is a scalar quantity :

(i) Force

(ii) Displacement

(iii) Work

(iv) Velocity

Answer:

Work

Question 9.

If the velocity of a body is doubled then kinetic energy will be :

(i) Same

(ii) Doubled

(iii) Tour times

(iv) Half times

Answer:

Four times

Question 10.

Work done in unit time is known as :

(i) Power

(ii) Energy

(iii) Force

Answer:

Power

Question 11.

1 kilowatt = ________.

(i) \(\frac{2}{3}\) HP

(ii) \(\frac{4}{3}\) HP

(iii) \(\frac{7}{3}\) HP

Answer:

\(\frac{4}{3}\) HP

Question 12.

What is the unit of kinetic energy in SI system :

(i) erg

(ii) HP

(iii) joule

Answer:

joule

Question 13.

1 mega-watt = _________.

(i) 10^{3} watt

(ii) 10^{4} watt

(iii) 10^{5} watt

(iv) 10^{6} watt

Answer:

10^{5} watt

Question 14.

What is the practical unit of power in CGS system :

(i) erg

(ii) watt

(iii) joule

Answer:

watt

Question 15.

Kilogram-meter is the unit of :

(i) energy

(ii) power

(iii) work

Answer:

Work

Question 16.

The dimension of work is :

(i) [M L^{2} T^{-2}]

(ii) [M^{2} L^{2} T^{2}]

(iii) [M L^{3} T^{-2}]

Answer:

[ML^{2} T^{-2}]

Question 17.

The dimension of power is :

(i) [M L^{2} T^{-3}]

(ii) [M^{2} L^{2} T^{2}]

(iii) [M L^{3} T^{3}]

Answer:

[ML^{2} T^{-3}]

Question 18.

1 watt = ______.

(i) 10^{5} erg/sec

(ii) 10^{6} erg/sec

(iii) 10^{7} erg/sec

Answer:

10^{7} erg/sec.

Question 19.

SI unit of energy is :

(i) Joule

(ii) erg

(iii) dyne

(iv) newton

Answer:

Joule

Question 20.

The potential energy of a boy is maximum when he is :

(i) sitting on the floor

(ii) standing on the floor

(iii) sleeping on the floor

Answer:

Standing on the floor.

Question 21.

Water stored in a dam possesses :

(i) KE

(ii) PE

(iii) elecric energy

(iv) no energy

Answer:

Electric energy

Question 22.

The kinetic energy of an object is K. If its mass is reduced to half, them its kinetic energy will be :

(i) K

(ii) 2 K

(iii) \(\frac{K}{2}\)

Answer:

\(\frac{K}{2}\)

Question 23.

The work done on an object does not depend upon the :

(i) force applied

(ii) initial velocity

(iii) displacement

Answer:

Initial velocity

Question 24.

In case of negative work, the angle between the force and displacement is :

(i) 0°

(ii) 45°

(iii) 180°

Answer:

180°

Question 25.

In a tug of war, work done by a losing team is :

(i) Zero

(ii) Positive

(iii) negative

Answer:

Negative

Question 26.

A stone is thrown vertically upward. It comes to rest momentarily at the highest point. What happens to its kinetic energy ?

(i) It convents into elastic potential energy

(ii) It convents into gravitational potential energy

(iii) It converts into chemical energy.

Answer:

It convents into gravitational potential energy.

Question 27.

A force of 100 N acting on a body does 100 j work. The distance through which the body is displaced –

(i) 5 m

(ii) 10 cm

(iii) 10 m

Answer:

10 m

Question 28.

When electric current passes through an electric bulb, electric energy is converted into :

(i) heat energy only

(ii) light energy only

(iii) both heat and light energy

Answer:

Both heat and light energy.

Fill in the blanks :

1. The gravitational unit of work in the _____ system is newton-meter.

Answer:

SI

2. Power is the ratio between work and _____

Answer:

time

3. Just before touching the ground, a freely falling body possesses only ______ energy.

Answer:

kinetic energy

4. Watt is the unit of ______ in SI system.

Answer:

power.

5. A raised hammer possesses ______ energy.

Answer:

potential

6. Water current or air current mainly possesses ______ energy.

Answer:

kinetic energy

7. 1 horse power = ______ watt.

Answer:

746

8. Both power and energy are ______ quantities.

Answer:

scalar

9. 1 joule = ________ erg.

Answer:

10^{7}

10. Potential energy of body is taken as ________

Answer:

mgh

11. 1 kilowatt = _______ Horse power.

Answer:

134

12. Power × time = ________

Answer:

work done

13. Work is a _______ quantity.

Answer:

scalar

14. newton × meter = _______.

Answer:

joule

15. The capacity of a body or a person to do work is its ________

Answer:

energy

16. kinetic energy = _______ × m × v^{2}

Answer:

\(\frac{1}{2}\)

17. When a force acts _______ to the direction of displacement of the particle, the force does not do any work.

Answer:

perpendicular

18. If there is no _______ of the point of application of the force, then the force is called no work force.

Answer:

displacement

19. If the direction of displacement (S) makes an angle θ with the direction of the applied force (F), component of the force along the direction of displacement will be ________

Answer:

FS\cos\θ

20. The ______ work is done, when the displacement is in the direction of the force.

Answer:

positive

21. In SI, the absolute unit of work is ______.

Answer:

joule

22. work done per unit time is called _______.

Answer:

power

23. One horse power is equal to _______ watt.

Answer:

746

24. The capacity of a body to do work is ______.

Answer:

energy

25. A stretched spring has potential energy due to its ______.

Answer:

shape.

26. The gravitational potential energy of body when raised from ground to certain height is _______ of the path followed.

Answer:

independent

27. Larger the mass of a body ______ is the kinetic energy of the body.

Answer:

greater

28. Total energy of a system is ______ , when energy is changed from one form to other.

Answer:

conserved

29. The mechanical energy is of _______ types.

Answer:

two