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Subject: Physics, asked on on 17/11/12
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Subject: Physics, asked on on 3/12/14
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Ashwin & 17 others asked a question
Subject: Physics, asked on on 26/4/14

1. State Newton's law of gravitation. Hence define universal gravitational constant. Give thevalue and dimensions of G.

2. Define acceleration due to gravity. Show that the value of 'g' decreases with altitude or height.

3. Discuss the variation of ‘g' with depth. What happens to 'g' at the centre of earth?

4. Write down the formula of gravitational potential energy and obtain from it an expression for
gravitational potential
.

5. What do you mean by gravitational potential energy of a body? Obtain an expression for it for
a body of mass m lying at distance r from the centre of the earth
.

6. Define the term orbital speed. Establish a relation for orbital speed of a satellite orbiting very
close to the surface of the earth. Find the ratio of this orbital speed and escape speed.

7. What are geostationary satellites? Calculate the height of the orbit above the surface of the
earth in which a satellite, if placed, will appear stationary.

8. State Kepler's law of planetary motion.

9. What is a polar satellite? Explain how does it scan the entire earth in its each revolution? Give
two important uses of a polar. Satellite.

10. What do you mean by the term weightlessness? Explain the state of weightlessness of (i) a freely falling body (ii) an astronaut in a satellite orbiting the earth.

11. Obtain an expression for the acceleration due to gravity on the surface of the earth in terms of mass of the earth and its radius. Discuss the variation of acceleration due to gravity with
altitude and depth.

12. State the conditions necessary for a satellite to appear stationary.

Diya Mallick asked a question
Subject: Physics, asked on on 23/12/14

36. A satellite of mass 1000 kg moves in a circular orbit of radius 7000 km around the earth.Calculate the total energy required to place the satellite in orbit from earth's surface. Take Radius of earth = 6400 km and g =10.0
ms-2.

37. An astronaut puts a ball of mass 7.2kg into a circular orbit about the earth at a height of 350 km.(i) what is the kinetic energy of the ball (ii) what is the potential energy of the ball?

38. An earth satellite makes a circular around the earth in 90 minutes. Calculate the height of satellite above theearth's surface. Radius of earth = 6400 kmand g = 9.8ms-2

39. An artificial satellite is revolving at a height of 500 km above the earth's surface in a circular orbit, completing one revolution in 98 minutes. Calculate the mass of the earth. Given, G = 6.67 x 10-11 N m-2 kg-2 and Re = 6.4 x 106 m.

40. If the period of revolution of an artificial satellite just above the earth by T and the density P, then prove that p T-2 is a universal constant.Calculate the value of this constant if G = 6.67 x 10-11 N m-2
kg-2

41. With what velocity must a body be thrown upward from the surface of the earth so that it reaches a height of 10 R = 6400 km. Mass of earth, M = 6 x 1024
kg and G=6.67 x 10-11 N m2 kg-2.

42. An artificial satellite is moving in a circular orbit around the earth with a speed equal to half the magnitude of escapevelocity from the earth (i) Determine the height of satellite above the earth's surface. (ii) If the satellite is stopped suddenly in its orbit and allowed to fall freely into the earth, find the speed with which it hits the surface of the earth. Take g = 9.8 m s-2 and Re= 6400 km.

43. An artificial satellite of mass 200 kg revolves around the earth in an orbit of average radius 6670 km. Calculate its orbital K.E., the gravitational potential energy and the total energy = 6.0 x 1024 kg and G = 6.67 x 10-11 N m2 kg-2.

44. If the distance of the planet jupiterfrom the sun is 5.2 times that of the earth, calculate the period of jupiter's revolution around the sun.

45.The ratio of thetimeperiods of revolution of mars and earth around the sun is 1.88. Find the ratio of the distances of these planets from the sun.

46.Moon describes a circular orbit of radius 4 x 10​8m around the earth in 28 days. Titan desctribes a circular orbit of radius 1.6 x 109 in around the saturn in 16 days. Compare the masses of saturn and the earth.

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