Calculate the force of gravitation between the earth and the Sun, given that the mass of the earth = 6 × 1 0 24 kg and of the Sun = 2 × 1 0 30 kg . The average distance between the two is 1.5 × 1 0 11 m and the gravitational constant is G = 6 . 7 × 10 - 11 N m 2 kg - 2 .

The force of attraction between the earth and the Sun is given by: F = G M s M e r 2 Here, M s = Mass of the Sun = 2 × 10 30 k g M e = Mass of the Earth = 6 × 10 24 k g r = Average distance between the earth and the Sun = 1 . 5 × 10 11 m G = Universal gravitational constant = 6.7 × 10 - 11 N m 2 kg - 2 On substituting the values, we get F = 6.7 × 10 - 11 × 2 × 10 30 × 6 × 10 24 1.5 × 10 11 2 N = 3.57 × 10 22 N

E M B I B E

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 10 - Gravitation>Exercises>Q 12

MEDIUM

9th CBSE

IMPORTANT

Earn 100

Gravitational force on the surface of the moon is only $\frac{1}{6}$ as strong as gravitational force on the earth. What is the weight in newtons of a $10 kg$ object on the moon and on the earth?

Important Questions on Gravitation

HARD

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 10 - Gravitation>Exercises>Q 13

A ball is thrown vertically upwards with a velocity of

49 m / s

. Calculate (Take

g = 9.8 m / s^{2}

)
(i) the maximum height to which it rises,
(ii) the total time it takes to return to the surface of the earth.

HARD

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 10 - Gravitation>Exercises>Q 14

A stone is released from the top of a tower of height

19.6 m

. Calculate its final velocity just before touching the ground.(Take g=

9.8 m / s^{2}

)

HARD

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 10 - Gravitation>Exercises>Q 15

A stone is thrown vertically upward with an initial velocity of

40 m / s

. Taking

g = 10 m / s^{2}

, find the maximum height reached by the stone. What are the net displacement and the total distance covered by the stone?

MEDIUM

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 10 - Gravitation>Exercises>Q 16

Calculate the force of gravitation between the earth and the Sun, given that the mass of the earth =

6 \times 1 0^{24} kg

and of the Sun =

2 \times 1 0^{30} kg

. The average distance between the two is

1.5 \times 1 0^{11} m

and the gravitational constant is

G = 6.7 \times 10^{- 11} N m^{2} {kg}^{- 2}

.

HARD

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 10 - Gravitation>Exercises>Q 17

A stone is allowed to fall from the top of a tower

100 m

high and at the same time, another stone is projected vertically upwards from the ground with a velocity of

25 m / s

. Calculate when and where the two stones will meet. (Use

g = 10 m / s^{2}

)

MEDIUM

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 10 - Gravitation>Exercises>Q 18

A ball thrown up vertically returns to the thrower after 6 s. (Use g = $10 m / s^{2}$ )Find
(a) the velocity with which it was thrown up,
(b) the maximum height it reaches, and
(c) its position after 4 s.

EASY

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 10 - Gravitation>Exercises>Q 19

In what direction does the buoyant force on an object immersed in a liquid act?

EASY

9th CBSE

IMPORTANT

SCIENCE TEXTBOOK FOR CLASS IX>Chapter 10 - Gravitation>Exercises>Q 20

Why does a block of plastic released under water come up to the surface of the water?