Question

In space do rockets close their fuel tank because by applying first law of motion if the body is moving with constant velocity then it will continuously moving unless external force is applied but in space no external forces is there so the rocket will continuously move. Is it true. Plz explain clearly?

Answer 1

Explanation:

As the rocket engines operate, they are continuously ejecting burned fuel gases, which have both mass and velocity, and therefore some momentum. By conservation of momentum, the rocket’s momentum changes by this same amount (with the opposite sign). We will assume the burned fuel is being ejected at a constant rate, which means the rate of change of the rocket’s momentum is also constant. By (Figure), this represents a constant force on the rocket.