Assertion: The projectile has only vertical component of velocity at the highest point of its trajectory.
Reason: At the highest point only one component of velocity present.
Assertion: Thrust on a rocket depends not only on the rate of decrease of mass.
Reason: Thrust also depends upon exhaust speed of the gases.
Assertion: When a ball collides elastically with a floor, it rebounds with the same velocity as with it strikes.
Reason: Momentum of earth + ball system remains constant.