Work & Energy- Class-IX-Vasu Classes


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Work & Energy- Class-IX-Vasu Classes

1. Work done is maximum when the angle between the force applied and direction of motion is

a) 90 degree
b) 0
c) 45
d) 60

2. What is the unit of work?

a) watt
b) joule
c) newton-m
d) Newton
e) B and C

3. The work done by centripetal force is

a) zero
b) maximum
c) Depends upon the direction of motion of the object
d) None

4. A person is walking on the horizontal road carrying a suitcase. The work done by him will be

a) W=FSCos 0
b) W=FS Cos 90
c) W=FS
d) W=FS Sin90

5. The unit of energy is

a) Erg
b) NM
c) Joule
d) KWH
e) A ,C and D

6. Which energy is always positive

a) KE
b) PE

7. A stretched bow has

a) PE
b) KE
c) Mechanical Energy
d) Muscular energy

8. If you apply 1 joule of energy to lift abook of 0.5kg ,how high it will rise?

a) 200cm
b) 20cm
c) 40cm
d) none

9. What is the force required to lift a book of mass m? The force is required to balane the force

a) centripetal force
b) gravitational force
c) force of friction
d) None of the above

10. What is the commercial unit of energy?

a) KW
b) KWH
c) Joule
d) HP

11. An Electric heater of 2KW is used for 2hrs. The energy consumed will be

a) 1KWH
b) 6KWH
c) 4KWH
d) 0.4KWH

12. The time required to spend an energy of 100J by a machine of power 10W

a) 100S
b) 50S
c) 10S
d) 25S

13. Rate of work done is called

a) Energy
b) Potential energy
c) KE
d) Power

14. An electric cell changes

a) Heat energy into light energy
b) Potential into Light energy
c) Chemical energy into electrical enregy
d) Chemical into heat and light energy

15. Two particles have masses 1gmand 2gms. What is the ratio of their kinetic energies?

a) 1:8
b) 1:16
c) 1:4
d) 3:5

16. A body of mass 5 kg is dropped from a height of 1m. Its KE just before it reaches the ground will be

a) 49J
b) 98J
c) 168J
d) 28J

17. The commercial unit of Electrical energy is

a) Joule
b) Ns
c) KWH
d) KW

18. A body is in rest .It may possess

a) Energy
b) momentum
c) speed
d) velocity

19. Work done by centripetal force is

a) always zero
b) always positive
c) always negative
d) may be positive zero or negative

20. A centripetal force acts

a) Radially inwards
b) radially outwards
c) tangentially
d) axially

21. Which of the following converts sound energy into electrical energy

a) loudspeaker
b) Electrochemical cell
c) television
d) micophone

22. An aeroplane flying at an altitude has

a) potential energy
b) kinetic energy
c) Both A and B
d) neither PE nor KE

23. How much mass must be raised to a height of one metre so that the work done is 1joule

a) 1kg
b) 100gm
c) 500gm
d) 2kg

24. When a body does work. It

a) loses energy
b) gains energy
c) Neither gains nor loses

25. If linear momentum of a body is increased by 5%,The K.E will increase by

a) 50%
b) 100%
c) 10%
d) 125%

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