Assertion (A) When a gun is fired i.e., it pushes back, with much less velocity than the velocity of the bullet.Reason (R) Velocity of the recoiling gun is less because the gun is much heavier than bullet.
Assertion (A) A body moving in a circular path is acted upon by the centripetal force.Reason (R) Centripetal force acting on the body is doing work to keep it rotating in the circular path.
Assertion (A) Short wave based are used for transmission of radio waves to a large distance.Reason (R) Short waves are reflected form ionosphere.
Assertion (A) The solids are more elastic and gases are least elastic.Reason (R) It is so because for the given stress applied the gases are more compressible than that of solids.
Assertion (A) Water kept in an open vessel will quickly evaporate on the surface of the moon.Reason (R) The temperature at the surface of the moon is much higher then boiling point of water.
Assertion (A) Light shows the phenomena of interference, diffraction and polarization,Reason (R) Because light behaves as corpuscles.
Assertion (A) When two system, which are in thermal equilibrium with a third system, then all system will be in thermal equilibrium with each other.Reason (R) The heat flows spontaneously form a system at a higher temperature to a lower temperature in a system.
Assertion (A) A dentist uses a concave miror to examine a small cavity.Reason (R) A dentist uses a concave mirror which can form a magnified virtual image of an object.
Assertion (A) The average velocity of the object over an interval of time is either smaller than or equal to the average speed of the object over the same interval.Reason (R) Velocity is a vector quantity and speed is a scalar quantity.
Assertion (A) The centripetal forces and centrifugal forces never cancel out.Reason (R) They do not act at the same time.