# Important questions of gravitation

In this topic important questions of gravitation is given which will be very important for students studying in class 11th .

## This topic covers all important questions of gravitation Important question
Gravitation
*****Derivation /define/relations based questions
1.State Newtons law of gravitation in vector form .(I)Haw can you find the mass of earth ,starting from the law of gravitation?)II) What are the factors affecting the value of G ? (III) If mass of two bodies are doubled and distance is halved , how will the gravitational force change ?
2. Define gravitational acceleration , find the expression for it, also find its value on the surface of earth .Haw the value of g changes (I) With altitude (II)with the depth .A planet reduces its radius by 1% with its mass remaining same , haw acceleration due to gravity changes ?
3. Define gravitational field and gravitational field intensity at a point , also find the expression for field intensity at a point.
4. Define gravitational potential, and gravitational potential energy at a point ,derive the expression for gravitational potential at a point also find the relation with potential energy.
5. Write the differences between                                                                                         (I) Inertial and gravitational mass,                                                                                 (II) G and g                                                                                                                           (III)escape velocity and orbital velocity on earth.
6.What is escape velocity ? obtain the expression for the escape velocity on earth . why there is no atmosphere on moon? Explain.
7.state and prove Kepler’s laws of planetary motion.
8. what is geostationary satellite ? calculate the height of the orbit above the surface of the earth in which a satellite is placed , will appear stationary, and also write the conditions for the launching of geo stationary satellite.
9.define the term orbital velocity , find the expression for (a) orbital velocity(b) time period and(c) total energy of the satellite . obtain the relation for orbital speed and escape velocity of the satellite from earth surface.
***numericals***
10. A 10 kg mass is divided into two parts , such that the force of attraction between them is maximum , what is the mass of each portions?
11. two stationary particles of masses M and m are separated by distance d apart . a third particle of mass m1 is placed on the line joining the two particles , experience no resultant gravitational force , what is the distance of the particle from m ?
12. haw far above the earth’s surface does the value of g becomes 20% of its value on the surface of earth ?
13. find the relation between height h above the earth surface with the depth from the earth surface where the value of g will be same.
14. what is the percentage increase in velocity for moon to escape from the gravitational pull of the earth ?
15.Two masses each of mass 100 kg are separated by distance 1m , find the gravitational (a) field and (b) potential at the mid point of the line joining them.
16.A satellite of mass 2000kg is raised from a circular orbit of radius 2R to a circular orbit of radius 3R . what is the approximate work done ?
17.  If the earth supposed to be a uniform sphere , suddenly contract and its radius becomes half of its original value , what will be the duration of day (or what will be time of rotation of earth on its own axis/ what will be the %change in duration of day)?
18. The weight of a body on the surface of earth is 250 N . calculate its weight at the distance equal to half of radius of earth below the surface of earth ( radius of earth =6400 km)
19. A rocket is launched from the surface of earth vertically with an initial speed of 10 m/s . haw far above the surface of earth would it go ? radius of the earth is 6400 km.
20. A satellite of mass 200 kg is rotating in an orbit at a height of 400 km from the surface of earth , haw much energy must be given to the rocket to take the satellite out of the earth ‘s gravitational influence? Mass of earth=6.0 x 10^24 kg; radius of earth=6400 km.
21. Three particles each of mass m are placed at the vertices of an equilateral triangle of side l . Find the work which should be done on this system to increase the sides of triangle 2l.
22. At what rate should the earth rotate so that the apparent g on the equator becomes zero? What will be the length of day in this situation? Find the energy required to launch a satellite of mass 1000 kg from the surface of earth to the height 2000 km above the earth surface.
23. Find the potential energy of a system of four particles placed at the vertices of a square of side l . also obtain the gravitational potential and gravitational field intensity at the center of the square.
24. Why space craft usually launched from west to east ? why is it more advantageous to launch rockets in the equatorial plane?

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• July 7, 2020 at 2:37 am