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# Work And Energy - Class 9 Science (Compulsory Test)

## 30 Questions MCQ Test | Work And Energy - Class 9 Science (Compulsory Test)

Description
This mock test of Work And Energy - Class 9 Science (Compulsory Test) for Class 9 helps you for every Class 9 entrance exam. This contains 30 Multiple Choice Questions for Class 9 Work And Energy - Class 9 Science (Compulsory Test) (mcq) to study with solutions a complete question bank. The solved questions answers in this Work And Energy - Class 9 Science (Compulsory Test) quiz give you a good mix of easy questions and tough questions. Class 9 students definitely take this Work And Energy - Class 9 Science (Compulsory Test) exercise for a better result in the exam. You can find other Work And Energy - Class 9 Science (Compulsory Test) extra questions, long questions & short questions for Class 9 on EduRev as well by searching above.
QUESTION: 1

### When a light and a heavy body have equal K.E, then which one has a greater momentum?

Solution: Heavy body have more momentum. bcz momentum = mass.velocity .so the mass of the heavy body is more than the light body.
QUESTION: 2

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QUESTION: 3

### Kilowatt hour (kWh) represents the unit of:

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QUESTION: 4

When speed of a motor car increases six times, then kinetic energy increases by

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QUESTION: 5

1 kWh equals:

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QUESTION: 6

When speed of the moving object is doubled its

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QUESTION: 7

When time taken to complete a given amount of work increases, then

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QUESTION: 8

When the force applied and the displacement of the body are inclined at 90° with each other, then work done is

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QUESTION: 9

The KE. of a body in increased most by doubling its

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QUESTION: 10

If a force F is applied on a body and it move with velocity v, then power will be :-

Solution:

Power = Work/ Time.
Work = Force x displacement
So, now Power = Force x displacement / Time.
But displacement / Time = velocity
According to the question, Force is F and V is velocity so,
Power = F x v

But power is a scalar quantity so, we have dot product for power so......
Power = Fv or F.v

QUESTION: 11

Work done by a centripetal force

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QUESTION: 12

A 1 kg mass falls from a height of 10 m into a sand box. What is the speed of the mass just before hitting the sand box? If it travels a distance of 2 cm into the sand before coming to rest, what is the average retarding force?

(Please note that Value of g = 9.8 m/s2)

Solution:
QUESTION: 13

Work done in moving a 50 kg block through a horizontal distance of 10 m by applying a force of 100N which makes an angle of 90° with the horizontal is

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QUESTION: 14

kWh is the unit of

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QUESTION: 15

An elevator is designed to lift a load of 1000 kg through 6 floors of a building averaging 3·5 m per floor in
6 sec. Power of the elevator, neglecting other losses, will be

(Please note that Value of g = 9.8m/s2)

Solution: Power =work/time =force ×displacement/time = mass×acceleration due to gravity× displacement /time = 1000×9.8×3.5×6/6= 3.43× 10*4 watt.
QUESTION: 16

The work done by a body is directly proportional to :

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QUESTION: 17

Work done is said to be positive when a force causes displacement:

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QUESTION: 18

How much time will be required to perform 520 J of work at the rate of 20 W?

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QUESTION: 19

In which case work is not done:

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QUESTION: 20

In which case work is done:

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QUESTION: 21

A stone is tied to a string and whirled in a circular path. The work done by the stone is :

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QUESTION: 22

A man carries a suitcase in his hand climbs up the stairs. The work done by the man is :

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QUESTION: 23

A rocket rises up in the air due to the force generated by the fuel. The work done by the:

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QUESTION: 24

One joule work is said to be done when a force of one newton acts through a distance of:

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QUESTION: 25

Work is the product of time and:

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QUESTION: 26

In angle in between the direction of applied force and displacement, for maximum work should be :

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QUESTION: 27

When energy changes from one form to another, the energy that disappears from one form, reappears in exactly equivalents amount in the other form.

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QUESTION: 28

In order to get minimum work, the angle between force and displacement should be 90°.

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QUESTION: 29

When a body falls on the ground and stops, the principle of conservation of energy is violated.

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QUESTION: 30

When an arrow is released from a bow, potential energy changes into kinetic energy.

Solution: