Page 3 - HA

2. If the moon attracts the earth, why does the earth not move towards the moon?
3. According to Newton's law of gravitation, the apple and the earth experience
equal and opposite forces due to gravitation. But it is the apple that falls towards the
earth and not vice-versa. Why?
4. According to Newton's law of gravitation, every particle of matter attracts every
other particle. But bodies on the surface of earth never move towards each other on
account of this force of attraction. Why?
NUMERICALS

22
24
1. The mass of the earth is 6 × 10 kg and that of the moon is 7.4 × 10 kg. If the
5
distance between the earth and the moon is 3.84×10 km, calculate the force
2
-2.
exerted by the earth on the moon. G = 6.7 × 10 –11 N m kg
2. Calculate the force of attraction between two balls each of mass 1 kg each,
−2
2
when their centers are 10 cm apart. GivenG = 6.67 × 10 −11 Nm kg .(BOARD)
30
27
3. The mass of planet Jupiter is 1.9 × 10 kg and that of the sun is 1.99 × 10 kg.
11
The mean distance of the Jupiter from the Sun is 7.8 × 10 m Calculate the
gravitational force which the sun exerts on Jupiter.(BOARD)
4. Find the gravitational attraction between two H‐atoms of a hydrogen molecule.
−2
2
Given G = 6.67 × 10Nm kg , mass of the atom = 1.67 × 10 −27 kg and distance
between two H‐atoms =10 -10 m(BOARD)
5. How does the force of gravitation between two objects change when the distance
between them is reduced to half. (AVG)

6. What happens to the force between two objects, if (AVG)
(i) the mass of one object is doubled?
(ii) the distance between the objects is doubled and tripled?

(iii) the masses of both objects are doubled?

1