16.The physical quantity obtained by the division of linear momentum of a
   body to its velocity is : [BPSC (Pre) 2002]
   (a) velocity
   (b) acceleration
   (c) mass
   (d) force
Ans: (c)
17.The bodies executing free falling motion have: [RRB TC/CC 2002]
   (a) equal momentum
   (b) equal velocity
   (c) equal acceleration
   (d) equal force
Ans: (b)
18.The increasing amount of carbon dioxide in the air is slowly raising the
   temperature of the atmosphere because it absorbs? [CSAT, 2012]
   (a) the water vapour or the air and retains its heat
   (b) the ultraviolet part of the solar radiation
   (c) all the solar radiation
   (d) the infrared part of the solar radiation
Ans: (d)
19.Rocket operates (works) on the principle of : [RRB Assitt. Driver 2003]
   (a) Energy conservation
   (b) Bernoulli"s theorem
   (c) Avogadro"s concept
   (d) Momentum conservation
Ans: (d)
20.The blackboard seems black because it : [CDS, 2011]
   (a) reflects every colour
   (b) does not reflect any colour
   (c) absorbs black colour
   (d) reflects black colour
Ans: (b)