Class 9th Physics Unit 5 Gravitation

physics 9th notes Chapter No 5

1. Who predicted about artificial satellites about 300 years ago?

 
 
 
 

2. Radius of the Earth is?                                                       

 
 
 
 

3. Distance of moon from Earth is?

 
 
 
 

4. What will be the value of G if mass of the earth becomes four times:

 
 
 
 

5. Moon completes its revolution around the Earth in:

 
 
 
 

6. Speed of GPS satellite is:

 
 
 
 

7. Weight of the body of mass 10 kg on the surface of moon:

 
 
 
 

8. Relative velocity of geostationary satellite with respect to earth is:

 
 
 
 

9. If mass of both the bodies is 1kg and distance between their centers is 1m then the gravitational force will be equal to:

 
 
 
 

10. An artificial satellite keeps on revolving around the earth in different orbits with uniform speed due to the?

 
 
 
 

11. If the weight of an object on the surface of earth is W. Its weight on the surface of moon will be:

 
 
 
 

12. A satellite is revolving around the earth in a circular orbit. If the radius of the orbit is increased from R to 2R. What will be its velocity?

 
 
 
 

13. On mountains our weight will be _____ as compared to weight on the surface of earth.

 
 
 
 

14. The force which pulls the object towards the center of circle is known as force:

 
 
 
 

15. What is not true about g?

 
 
 
 

16. For making the rocket to revolve around the earth it must be sent velocity of:

 
 
 
 

17. Unit of gravitational field strength is:

 
 
 
 

18. As we go up the value of G becomes:

 
 
 
 

19. If the distance between two masses is half then the force of gravitation becomes:

 
 
 
 

20. The mass of Earth is approximately:

 
 
 
 

21. Radius of earth is:

 
 
 
 

22. Gravitational force on the surface of earth is equal to:

 
 
 
 

23. Height of the Geostationary satellite above the surface of earth is:

 
 
 
 

24. In System International, the value of G is:    

 
 
 
 

25. When an object is at a height equal to radius of earth above the surface of the earth. What is the value of g?

 
 
 
 

26. The SI unit of gravitational force is:

 
 
 
 

27. If a rocket is fired vertically with a speed of ____, it will start revolving around the earth:

 
 
 
 

Short Questions

Can you determine the mass of our moon? If yes, then what you need to know?
Define Force of Gravitation.
Define orbital velocity.
Do you attract the Earth or the Earth attracts you? Which one is attracting with a larger force? You or the Earth.
Does an apple attract the Earth towards it?
Does the weight of an apple increase, decrease or remain when taken to the top of a mountain?
Explain Newton’s law of gravitation?
Explain that the gravitational forces are consistent with Newton’s third law of motion?
Explain, what is meant by gravitational field strength?
How can you say that gravitational force is a field force?
How the mass of the Earth can be determined?
Moon revolves around the earth, from where it gets necessary centripetal force?
On what factors the orbital speed of a satellite depends?
State Law of gravitation.
What are artificial satellites?
What are geostationary satellites also write their uses.
What do you know about geostationary satellites?
What do you know about Global Positioning System (GPS)?
What is meant by the force of gravitation?
What is the field force?
What is the gravitational force acting on the body placed at the surface of Earth?
What is the relation between Law of Gravitation and Newton’s Third law of motion?
What will happen if Earth suddenly stops revolving around the Sun?
Who gave the idea of gravity?
Why communication satellites are stationed at geostationary orbits?
Why does the value of g vary from place to place?
Why don’t we observe force of attraction between any two objects around us?
Why earlier scientists could not guess about the gravitational force?
Why the law of gravitation is important to us?
With what force an apple weighing 1N attracts the Earth?

Long Questions

A communication satellite is launched at 42000 km above Earth. Find its orbital speed.              
A polar satellite is launched at 850 km above Earth. Find its orbital speed.
At what altitude the value of g would become one fourth than on the surface of the Earth? 
Calculate the value of g at a height of 3600 km above the surface of the Earth.
Derive the formula for the orbital speed of an artificial satellite?
Determine the mass of the earth by using Newton’s law of gravitation.
Explain the gravitational field?
Explain the law of gravitation.
Explain the motion of an artificial satellite and derive the formula for orbital velocity
Explain the variation of ‘g’ with altitude.
Find the acceleration due to gravity on the surface of the Mars. The mass of Mars is 6.42 × 10²³ kg and its radius is 3370 km.
Find the gravitational force of attraction between two spheres each of mass 1000 kg. The distance between the centers of the spheres is 0.5 m.
Find the value of g due to the Earth at geostationary satellite. The radius of the geostationary orbit is 48700 km
How Newton’s law of gravitation helps in understanding the motion of satellites?
How Newton’s law of gravitation helps in understanding the motion of satellites? On what factors the orbital speed of a satellite depends?
How the mass of Earth can be determined?
State and explain Newton’s law of gravitation.
The acceleration due to gravity on the surface of moon is 1.62 ms⁻². The radius of Moon is 1740 km. Find the mass of moon.
The gravitational force between two identical lead spheres kept at 1 m apart is 0.006673 N. Find their masses.
The value of g is 4.0 ms⁻² at a distance of 10000 km from the center of the Earth. Find the mass of the Earth.
What are artificial satellites? Define orbital velocities and what do you know about
What is the effect of the following on the gravitational acceleration?
Mass of a freely falling body.
Distance of freely falling body from the center of the Earth.
Is there any difference between the values of g at the equator and the poles? Explain.
Why does the value of g vary from place to place? Explain how the value of g varies with altitude.

 

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