Calculate the mass of the earth. Given radius of the earth = 6 . 4 × 10 6 m and g = 9 . 8 m / s 2 .

Given, The radius of the earth, R = 6 . 4 × 10 6 m The acceleration due to gravity, g = 9 . 8 m / s 2 The equation for acceleration due to gravity is, g = GM R 2 where M is the mass of earth and G = 6 . 67 × 10 - 11 N m 2 kg - 2 So the mass of the earth is, M = gR 2 G = 9 .8 × ( 6 .4 × 10 6 ) 2 6 .67 × 10 − 11 = 6 × 10 24 kg

What is the acceleration due to gravity at a height of R 5 from the surface of the earth?

The acceleration due to gravity at height h from the earth surface is, g h = g R R + h 2 where g is the acceleration due to gravity on the surface and R is the radius of the earth. g h = g R R + R 5 2 = g 5 R 6 R 2 = g 25 36 = 25 36 × 9 .8 = 6 .8 m/s 2

E M B I B E

Modern's abc+ Of Science - Physics For Class IX>Chapter 3 - Gravitation>Summative Assessment>Q 4

MEDIUM

9th CBSE

IMPORTANT

Earn 100

What is the difference between mass and weight. How does weight of an object change on moving from equator to poles? When can the weight of an object be zero?

Important Questions on Gravitation

EASY

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 3 - Gravitation>Summative Assessment>Q 1

The mass of the earth is

6 \times 10^{24} kg

and that of the Moon is

7.4 \times 10^{22} kg

. If the distance between the Earth and the moon is

3.8 \times 10^{5} km

, calculate the force exerted by the earth on the moon.

EASY

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 3 - Gravitation>Summative Assessment>Q 2

The gravitational force between two bodies is

4 N

. What will be the gravitational force between the bodies if the distance between them doubles?

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 3 - Gravitation>Summative Assessment>Q 3

Calculate the value of acceleration due to gravity on the surface of the planet Jupiter. Mass of Jupiter is

319

times the mass of the earth. Radius of Jupiter is

11.2

times the radius of earth.

EASY

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 3 - Gravitation>Summative Assessment>Q 4

Calculate the mass of the earth. Given radius of the earth

= 6.4 \times 10^{6} m

and

g = 9.8 m / s^{2}

.

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 3 - Gravitation>Summative Assessment>Q 5

A car falls a ledge and drops to the ground in $0.5 s$ . Let $g = 10 m s^{- 2}$ (for simplifying the calculations).

(i) What is its speed on striking the ground?

(ii) What is its average speed during the $0.5 s$ ?

(iii) How high is the ledge from the ground?

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 3 - Gravitation>Summative Assessment>Q 6

A player throws a ball vertically upward. The ball attains a height of

25 m

and then returns back. Find the initial speed of the ball.

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 3 - Gravitation>Summative Assessment>Q 7

A boy on a cliff

49 m

high drops a stone. One second later he throws another stone. Both the stone hit the ground at the same time. With what speed is the second stone thrown?

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 3 - Gravitation>Summative Assessment>Q 8

What is the acceleration due to gravity at a height of