Question Pool Gravitation

# Gravitation - SAMAGRA Question Pool & Answers | Class 9 English Medium

Kerala Syllabus SAMAGRA SCERT SAMAGRA Question Pool for Class 9 English Medium Physics Gravitation

Qn 1.

Imagine a spring balance is dropped from the top of a building along with a mass of 1 Kg.

1. What will be reading of the spring balance while falling down? Why ?

2. If the mass takes 5s to reach ground, find out height of the building.

3. What is the velocity of the mass just before it touches the ground ?

a)Zero. The weight of a freely falling object is fully utilized for it acceleration.

b)S =

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Qn 2.

The resultant gravitation force at the centre of the Earth is zero. Give reason.

When a body is placed at the centre of the earth, it is attracted towards all directions. Therefore, the resultant force of attraction at

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Qn 3.

Will the value of g be the same everywhere on the Earth ? Why ?

No. As Earth is not a perfect sphere, the distance from the centre of the Earth to its surface is not the same at different

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Qn 4.

An iron block of mass 1 Kg falls freely from the top of a building in 2 s.

1. calculate height of the building. (g = 10  m/s2)

2. If the experiment was repeated at the same altitude as the moon, how long would it take for the iron block to reach the lunar surface? ( g on moon = 1.62 m/s2)

a)S= ut + 1/2 at= 0+ 1/2 x 10 x2=20 m

b)S= ut + 1/2

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Qn 5.

If the distance between two objects attracting each other is increased by 4 times, what will be the force of attraction between them ?

F = G m1 m2 / d2

d = 4 d

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Qn 6.

Calculate the weight of an object of mass 40 Kg.

W=mg = 40x 9.8 =392

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Qn 7.

a.Calculate the mass of a man on moon whose mass on the Earth is 60 Kg.

b.What will be his weight on the Earth ? Will his weight differ on the moon ? If so why ?

1. 60 Kg ( Mass of an object remains the same everywhere in the Universe)

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Qn 8.

Imagine that a pipe is fixed through centre of the Earth (B) from the north pole (A) to the south pole (C).

IMage

1. If a ball rolls from A to B, what change will happen in the force of gravity experienced by the ball ?

2. What will be the weight of the ball at B ?

3. How will the weight of the ball change when it rolls from B to C ?

1. Force of gravity will decrease.

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Qn 9.

At which place on the surface of Earth does an object experiences the maximum force of gravity ? Give reason.

At poles. That is,

Force of gravity, F = G Mm/R2

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Qn 10.

Two objects of mass 35 Kg and 45 Kg are placed 2 m apart. Find out the force of attraction between them.

F = G m1 m2 / d2

= (6.67 X

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Qn 11.

Give reason -

Even though there is a force of attraction between two adjacent objects, they do not come closer attracting each other.

Gravitational force is a very weak force and hence it is unable to overcome the frictional and other force. Therefore two adjacent

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Qn 12.

Consider two stones of mass 5 Kg and 50 Kg placed somewhere 500 m above the Earth’s surface.

1. Which stone will experience more force of attraction by the Earth ? Why?

2. If both the stones are allowed to fall freely at the same time, which one will reach the Earth’s surface first ? Give reason.

3. Compare the weight of the stones while falling down.

a.50 g

F = GMm / R2 , the force of gravitation is directly proportion to

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Qn 13.

What do you mean by Gravitational force of attraction ? On what factors does the force of gravity depend ?

The Earth attracts all objects towards its centre. This force of attraction is called Gravitational force. The force of gravity depends