Physics CSIR Study material Part -3 - Gravitation


Fg and Fe represents gravitational and electrostatic forces respectively, between the two electrons situated at a distance of 10 m. The ratio Fg/Fe is of the order of

(a) 1043

(b) 1036

(c) 10-43

(d) 10-36


The value of ‘g’ at a particular point is 9.8 m/sec2 suppose the earth suddenly shrink uniformly to half its present size without losing any mass. The value of ‘g at the same point (assuming that the distance of the point from the centre of the earth does not shrink) will become

(a) 9.8 m/sec2

(b) 4.9 m/sec2

(c) 19.6 m/sec2

(d) 2.45 m/sec2


The planet mercury is revolving in an elliptical orbit around the sun as shown in figure. The kinetic energy of mercury will be greater at

(a) A

(b) B

(c) C

(d) D


The orbit velocity of an artificial satellite in a circular orbit just above the earth’s surface is v. For a satellite orbiting at an altitude of half of the earth’s radius, the orbital velocity is






If the change in the value of g at the height h above the surface of the earth is the same as at a depth x below it, then (both x and h being much smaller than the radius of the earth)

(a) x = h

(b) x = 2 h

(c) x =

(d) x = h2


21. Ans.: (c)
22. Ans.: (a)
23. Ans.: (a)
24. Ans.: (c)
25. Ans.: (b)