Question 71:
If the distance between
Solution :
Gravitational force is given by:
New Gravitational force F_{1} = F
Let on of the mass is changed to m_{1 }so as to maintain the same gravitational force
Hence the mass should be increased by 25 times in order to have the same gravitational force.
Question 72:
The universal law of gravitation states that every object exerts a gravitational force of attraction on every other object. if this is true, then why don't we see the various objects in a room moving toward one another?
Solution :
In order to be able to notice the gravitational force of attraction between any two objects, at least one of the objects on the earth should have an extremely large mass. Since no object on the earth
The two objects in a room do not move towards each other because due to their small masses, the gravitational force of attraction between them is very, very weak.
Question 73:
Suppose a planet exists whose mass and radius both are half those of the earth. Calculate the acceleration due to gravity on the surface of this planet.
Solution :
Acceleration due to
Acceleration due to gravity on the surface of
Lakhmir Singh Physics Class 9 Solutions Page No:104
Question 74:
A coin and a piece of paper are dropped simultaneously from the same height. Which of the two will touch the ground
Solution :
The coin reaches the ground first as compared to the piece of paper because it experiences lesser resistance from
If the coin and the piece of paper are dropped in
Question 75:
A stone and the earth attract each other with an equal and opposite force. Why then we see only the stone falling towards the earth but not the earth rising
Solution :
The mass of a stone is very small, due to which the gravitational force produces a large acceleration in it. Due to
Question 76:
What is the actual shape of the orbit of a planet around the
Solution :
The actual shape of the orbit of a planet around the sun is elliptical. The assumption made by the Newton regarding the shape of an orbit of a planet around the sun was that the orbit of a planet around the sun is ‘circular’.
Question 77:
The values of g at six distances A, B, C, D, E and F from the surface of the earth are found to be 3.08 m/s^{2}, 9.2.3 m/s^{2}, 0.57 m/s^{2}, 7.34 m/s^{2}, 0.30 m/s^{2} and 1.49 m/s^{2}, respectively.
(a)
(b) If the value of distance F be 10000 km from the surface of the earth, state whether this distance is
Solution :
(a) 9.23 m/s^{2} , 7.34 m/s^{2} , 3.08 m/s^{2} , 1.49 m/s^{2} , 0.57 m/s^{2} , 0.30 m/s^{2}
(b) This distance F of 10000 km is high up in the sky. The distance of 10000 km cannot be deep inside the earth because the radius of
1 videos228 docs21 tests

1. What is the equation for gravitational force between two objects? 
2. How does the gravitational force depend on the masses of the objects? 
3. What is the significance of the gravitational constant (G) in the equation for gravitational force? 
4. How does the distance between two objects affect the gravitational force between them? 
5. How does the gravitational force affect the motion of objects in the universe? 
1 videos228 docs21 tests


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