Q: Question 11: Give the formula for the gravitational force F between two bodies of masses M and m kept at a distance d from each other.

Answer: F=d2GMm where, F − gravitational force G − gravitational constant M − mass of the earth m − mass of object d − distance

Question 1

Question 2:
Which force is responsible for the moon revolving round the earth?

Accepted Answer

Answer:
Gravitational force is responsible for the moon to revolve around the earth.

Question 2

Question 3:
Does the acceleration produced in a freely falling body depend on the mass of the body?

Accepted Answer

Answer:
No, acceleration produced in a freely falling body does not depend on the mass of the body.

Question 3

Question 4:
Name the scientist who gave the three laws of planetary motion.

Accepted Answer

Answer:
Johannes Kepler gave the three laws of planetary motion.

Question 4

Question 5:
Name the scientist who explained the motion of planets on the basis of gravitational force between the sun and planets.

Accepted Answer

Answer:
Sir Isaac Newton explained the motion of planets on the basis of gravitational force between the sun and the planets.

Question 5

Question 6:
State the Kepler's law which is represented by the relation r3 ∝ T2.

Accepted Answer

Answer:
Kepler’s second law is represented by the given relation, which states that “each planet revolves around the sun in such a way that the line joining the planet to the sun sweeps over equal areas in equal intervals of time.

Question 6

Question 7:
Which of the Kepler's laws of planetary motion led Newton to establish the inverse-square rule for gravitational force between two bodies?

Accepted Answer

Answer:
The third law of Kepler’s planetary motion (i.e. The law of harmonies) led Newton to establish the inverse – square rule for gravitational force between two bodies.

Question 7

Question 8:
Name the property of earth which is responsible for extremely small acceleration being produced in it as a result of attraction by other small objects.

Accepted Answer

Answer:
The earth’s large mass is responsible for the extremely small acceleration produced in it as a result of attraction by other small objects.

Question 8

Question 9:
What is the acceleration produced in a freely falling body of mass 10 kg? (Neglect air resistance)

Accepted Answer

Answer:
The acceleration produced in a freely falling body of mass 10 kg would be 9.8m/s2.

Question 9

Question 10:
When an object is dropped from a height, it accelerates and falls down. Name the force which accelerates the object.

Accepted Answer

Answer:
Gravitational force of the earth accelerates an object when it is dropped from a height.

Question 10

Question 11:
Give the formula for the gravitational force F between two bodies of masses M and m kept at a distance d from each other.

Accepted Answer

Answer:
F=d2GMm​
where,
F − gravitational force
G − gravitational constant
M − mass of the earth
m − mass of object
d − distance

Question 11

Question 12:
What force is responsible for the earth revolving round the sun?

Accepted Answer

Answer:
Gravitational force is responsible for the earth’s revolution around the sun.

Question 12

Question 13:
What name has been given to the force with which two objects lying apart attract each other?

Accepted Answer

Answer:
Gravitational force is responsible for the attraction between two objects lying apart from each other.

Question 13

Question 14:
What type of force is involved in the formation of tides in the sea?

Accepted Answer

Answer:
Gravitational force exerted by the moon is responsible for the formation of tides in the sea.

Question 14

Question 15:
Which force is responsible for holding the solar system together?

Accepted Answer

Answer:
Gravitational force of the sun is responsible for holding the solar system together.

Question 15

Question 16:
What is the weight of a 1 kilogram mass on the earth? (g = 9.8 m/s2).

Accepted Answer

Answer:
W (weight of the body) =?
m (mass of the body) = 1 kg
g (acceleration due to gravity) = 9.8 m/s2
W= mg
   = 1 × 9.8
   = 9.8 N
Answer: Weight = 9.8 N

Question 16

Question 17:
On what factor/factors does the weight of a body depend?

Accepted Answer

Answer:
Since, weight, W= mg. so weight of a body depends on:
• Mass of a body.
• Acceleration due to gravity (g) at a given place.

Question 17

Question 18:
As the altitude of a body increases, do the weight and mass both vary?

Accepted Answer

Answer:
As the altitude increases, the mass (m) of the body remains constant but the weight (W = mg) of the body, because of decreasing acceleration due to gravity (g), decreases with an increase in altitude.

Question 18

Question 19:
If the same body is taken to places having different gravitational field strength, then what will vary : its weight or mass ?

Accepted Answer

Answer:
Only weight will vary because acceleration due to gravity (g) varies from place to place and mass remains constant.

Question 19

Question 20:
If the mass of an object be 10 kg, what is its weight? (g = 9.8 m/s2).

Accepted Answer

Answer:
W (weight of the body) =?
m (mass of the body) = 10 kg
g (acceleration due to gravity) = 9.8 m/s2
W= mg
   = 10 × 9.8
   = 98 N
Answer : Weight = 98N

Chapter 3 : Gravitation