# WBBSE Class 9 Physical Science MCQ Questions Chapter 5 Work, Power and Energy

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
Potential energy

Question 2.
What is the absolute unit of force in SI system ?
(i) 1 kg-m
(ii) 1 joule
(iii) 1 erg
1 Joule

Question 3.
What is the relation between power and force ?
(i) power = force × velocity
(ii) velocity = force × power
(iii) force = power × velocity
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
No work is done

Question 5.
The dimension of energy is :
(i) [M L2 T-2]
(ii) [M2 L2 T3]
(iii) [M L2 T3]
(iv) [M L3 T2]
ML2 T-2

Question 6.
1 Horse power = ______.
(i) 7.46 watt
(ii) 74.6 watt
(iii) 746 watt
(iv) 7460 watt
746 watt

Question 7.
All energies are transformed ultimately into :
(i) heat energy
(ii) kinetic energy
(iii) sound energy
(iv) electric energy
Heat energy

Question 8.
Which is a scalar quantity :
(i) Force
(ii) Displacement
(iii) Work
(iv) Velocity
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
Four times

Question 10.
Work done in unit time is known as :
(i) Power
(ii) Energy
(iii) Force
Power

Question 11.
1 kilowatt = ________.
(i) $$\frac{2}{3}$$ HP
(ii) $$\frac{4}{3}$$ HP
(iii) $$\frac{7}{3}$$ HP
$$\frac{4}{3}$$ HP

Question 12.
What is the unit of kinetic energy in SI system :
(i) erg
(ii) HP
(iii) joule
joule

Question 13.
1 mega-watt = _________.
(i) 103 watt
(ii) 104 watt
(iii) 105 watt
(iv) 106 watt
105 watt

Question 14.
What is the practical unit of power in CGS system :
(i) erg
(ii) watt
(iii) joule
watt

Question 15.
Kilogram-meter is the unit of :
(i) energy
(ii) power
(iii) work
Work

Question 16.
The dimension of work is :
(i) [M L2 T-2]
(ii) [M2 L2 T2]
(iii) [M L3 T-2]
[ML2 T-2]

Question 17.
The dimension of power is :
(i) [M L2 T-3]
(ii) [M2 L2 T2]
(iii) [M L3 T3]
[ML2 T-3]

Question 18.
1 watt = ______.
(i) 105 erg/sec
(ii) 106 erg/sec
(iii) 107 erg/sec
107 erg/sec.

Question 19.
SI unit of energy is :
(i) Joule
(ii) erg
(iii) dyne
(iv) newton
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
Standing on the floor.

Question 21.
Water stored in a dam possesses :
(i) KE
(ii) PE
(iii) elecric energy
(iv) no energy
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) $$\frac{K}{2}$$
$$\frac{K}{2}$$

Question 23.
The work done on an object does not depend upon the :
(i) force applied
(ii) initial velocity
(iii) displacement
Initial velocity

Question 24.
In case of negative work, the angle between the force and displacement is :
(i) 0°
(ii) 45°
(iii) 180°
180°

Question 25.
In a tug of war, work done by a losing team is :
(i) Zero
(ii) Positive
(iii) negative
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.
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
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
Both heat and light energy.

Fill in the blanks :

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

2. Power is the ratio between work and _____
time

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

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

5. A raised hammer possesses ______ energy.
potential

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

7. 1 horse power = ______ watt.
746

8. Both power and energy are ______ quantities.
scalar

9. 1 joule = ________ erg.
107

10. Potential energy of body is taken as ________
mgh

11. 1 kilowatt = _______ Horse power.
134

12. Power × time = ________
work done

13. Work is a _______ quantity.
scalar

14. newton × meter = _______.
joule

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

16. kinetic energy = _______ × m × v2
$$\frac{1}{2}$$

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

18. If there is no _______ of the point of application of the force, then the force is called no work force.
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 ________
FS\cos\θ

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

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

22. work done per unit time is called _______.
power

23. One horse power is equal to _______ watt.
746

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

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

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