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 L2 T-2]
(ii) [M2 L2 T3]
(iii) [M L2 T3]
(iv) [M L3 T2]
Answer:
ML2 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) 103 watt
(ii) 104 watt
(iii) 105 watt
(iv) 106 watt
Answer:
105 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 L2 T-2]
(ii) [M2 L2 T2]
(iii) [M L3 T-2]
Answer:
[ML2 T-2]
Question 17.
The dimension of power is :
(i) [M L2 T-3]
(ii) [M2 L2 T2]
(iii) [M L3 T3]
Answer:
[ML2 T-3]
Question 18.
1 watt = ______.
(i) 105 erg/sec
(ii) 106 erg/sec
(iii) 107 erg/sec
Answer:
107 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:
107
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 × v2
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