21.A stationary elevated object has
   (a) kinetic energy
   (b) potential energy
   (c) momentum
   (d) both potential and kinetic energy
Ans: (b)
22.A light year means ________.
   (a) a unit of length
   (b) a unit of time
   (c) a year of no consequence
   (d) illumination throughout the year
Ans: (a)
23.An astronomical unit of distance is _______.
   (a) a kilometre
   (b) light year
   (c) the average distance from the earth to the sun
   (d) None of the above
Ans: (b)
24.What is the minimum velocity required for a rocket to overcome earth"s
   gravity and travel into space?
   (a) 9.8 km/sec
   (b) 11.2 km/ sec
   (c) 25 km/ sec
   (d) 35 km/ sec
Ans: (b)
25.The motion of the pendulum of a wall clock is an example of
   (a) vibratory motion
   (b) linear motion
   (c) rotational motion
   (d) None of the above
Ans: (a)