The gravitational force produced between two heavenly bodies is 100N. what changes occur on the gravitational force of distance between them is doubled ?
Answers
Required answer
Question1.
How does the force of gravitation between two objects change when the distance between them is reduced to half?
Answer:
According to Universal law of gravitation, the force of attraction between 2 bodies is:-
F = (G m1m2)/r2
Where m1m2 = the masses of the two bodies,
r = distance between them
G = gravitational Constant
When the distance is reduced to half i.e. r’ = (1/2) r then,
F’ = (G m1m2)/r2
= (G m1m2)/(r/2)2
= (4 G m1m2)/ (r2) = 4F
Therefore when the distance between the objects is reduced to half, then the force of gravitation increases by four times the original force.
Question2.
Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object?
Answer:
All objects fall on ground with constant acceleration known as acceleration due to gravity (g).
It is constant and the value of ‘g’ does not depend upon the mass of an object.
Therefore heavy objects do not fall faster than light objects provided there is no air resistance.
Question 3.
What is the magnitude of the gravitational force between the earth and a 1 kg object on its surface?
(Mass of the earth is 6 × 1024 kg and radius of the earth is 6.4 × 106 m.)
Answer:
Given:
Mass of earth m1 =6 × 1024 kg
Mass of the object m2 = 1 kg
Radius of the earth =6.4 × 106 m
Universal gravitational constant G = 6.67 x 10-11 Nm2kg-2
By applying universal law of gravitation: - F = (G m1 m2/r2)
= (6.67 x 10-11 x 6 × 1024 x 1)/ (6.4 × 106)2
F = 9.8 N
Physics Class 9 Gravitation Image 4
Question 4.
The earth and the moon are attracted to each other by gravitational force.
Does the earth attract the moon with a force that is greater or smaller or the same as the force with which the moon attracts the earth? Why?
Answer:
The earth attracts the moon with an equal force with which the moon attracts the earth but these forces are in opposite directions.
By universal law of gravitation, the force between moon and the sun will be:
F = (G m1 m2/d2)
Where m1 m2 = masses of earth and moon respectively.
d = distance between the earth and moon.
Question 5.
If the moon attracts the earth, why does the earth not move towards the moon?
Answer:
According to universal law of gravitation and Newton third law, we know that the force of attraction between two objects is same but in opposite direction.
Thus the earth attracts the moon with the same force as the moon exerts on earth but in opposite directions.
Your answer
If the mass of one of the objects is doubled, then the force of gravity between them is doubled. .. If the separation distance between two objects is doubled (increased by a factor of 2), then the force of gravitational attraction is decreased by a factor of 4 (2 raised to the second power)