CBSE Class 9 Answered

A)  SLV works on the principle of Law of conservation of linear momentum. 

 

B) The principle of law of conservation of linear momentum states that the the sum of momentaof the two objects before collision is equal tothe sum of momenta after the collision provided there is no external unbalanced force acting on them.

Rocket while taking off from the ground, the chemicals inside the rocket burn and produce very high velocity blast of hot gases. These gases pass out through the tail nozzle of the rocket in the downward direction with tremendous speed and the rocket moves up to balance the momentum of the gases. The gases have a very high velocity ang hence a very large momentum. An equal momentum is imparted to the rocket in the opposite direction, so that it goes up with a high velocity.

C) There is not a single experiment which disapprove the law of conservation of linear momentum. The rocket works as it is in space when the gases are expelled from it. 

D) SI unit of momentum is kilogram - metre/seconds (kg m/s)