45.The force that keeps a body In a circular motion is called
   (a) the centripetal force
   (b) the centrifugal force
   (c) the frictional force
   (d) All the above
Ans: (a)
46.The earth satellite Aryabhatta was put in orbit by India on
   (a) October 20, 1978
   (b) November 14, 1978
   (c) January 26, 1979
   (d) April 19, 1975
Ans: (d)
47.The minimum velocity required by a satellite to escape earth"s gravitational
   pull is
   (a) 18 km/s
   (b) 11.2 km /s
   (c) 21 km/s
   (d) 35 km/s
Ans: (b)
48.When a satellite is In a geostationary orbit the force keeping it in orbit Is
   (a) zero
   (b) the centrifugal force
   (c) reaction. due to steady burning of fuel
   (d) the gravitational pull on the body by the earth is the weight of the body
       which provides the centripetal force
Ans: (d)
49.The period of a geostationary (synchronous) satellite orbiting the earth over
   the equator is
   (a) 16 hours
   (b) 12 hours
   (c) 20 hours
   (d) 24 hours
Ans: (d)