Question

5. So that the force of gravitation between two bodies may become noticeable and
cause motion one of the bodies must have an extremely large
They​

Answer 1

Explanation:

What is the value of gravitational constant G (i) on the earth, and (ii) on the moon ?

Solution :

Value of gravitational constant G on the earth and the moon is = 6.67 x 10-11 Nm2/kg2

Note that the value of G always remains constant irrespective of the location.

Question 2:

Which force is responsible for the moon revolving round the earth ?

Solution :

Gravitational force is responsible for the moon revolving round the earth.

Question 3:

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

Solution :

No, the acceleration produced in a freely falling body is independent of the mass of the body.

Question 4:

Name the scientist who gave the three laws of planetary motion.

Solution :

Johannes Kepler gave the three laws of planetary motion.

Question 5:

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

Solution :

Newton explained the motion of planets on the basis of gravitational force between the sun and planets.

Question 6:

State the Kepler’s law which is represented by the relation r3 ∝ T2.

Solution :

Kepler’s law of periods states that: The cube of the mean distance of a planet from the sun is directly proportional to the square of time it takes to move around the sun.

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 ?

Solution :

Kepler’s third law of planetary motion led Newton to establish the inverse-square rule for gravitational force between two bodies.

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.

Solution :

Extremely large mass of the earth.

Question 9:

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

Solution :

Acceleration produced in a freely falling body, irrespective of its mass, is 9.8m/s2

Question 10:

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

Solution :

Gravitational force of the earth.

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.

Solution :

The gravitational force F between two bodies of masses M and m kept at a distance d from each other is :

lakhmir-singh-and-manjit-kaur-physics-class-9-solution-Chapter-3-Gravitation-Q11

Question 12:

What force is responsible for the earth revolving round the sun ?

Solution :

Gravitational force is responsible for the earth revolving round the sun.

Question 13:

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

Solution :

Gravitational force causes two objects lying apart attract each other.

Question 14:

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

Solution :

Gravitational force (exerted mainly by the moon and to some extent by the sun) is involved in the formation of

Answer 2

(a) The acceleration due to gravity on the moon is about one-sixth of that on the earth. (b) In order to the force of gravitation between two bodies to become noticeable and cause motion, one of the bodies must have an extremely large mass.