A basic question abour space.?

Question

A friend of mine claims that a stationary rocket cannot move in the space because it has nothing to push against.

There is no air over there to to provide it a reactant push due to the exhaust of gases.

Since I am not vey familiar with space physics, I couldnt prove to him that the rocket can move over there.

Answer 1

Rockets do not push against the air to move.  They push against the exhaust of their engines.

Try this with your friend.  Stand face-to-face with your feet together.  Now, without bending your knees or waist, give your friend a push.  What will happen is that, as your friend gets pushed back, you will fall in the opposite direction.  You pushing your friend causes an equal force to push you back.

Similarly, the rocket pushes the exhaust out the back of its engines.  This causes the rocket to be pushed forward.

Answer 2

thats not true..rockets work on the principle of conservation of momentum, in a system, a mass with velocity backwards should be compensated with a mass with velocity forward by the equation m1v1=m2v2

Answer 3

The exhaust gases have mass, and when they expand out of the rocket they are pushing against the rocket. The rocket and gases push against each other and travel in opposite directions.

Result:  The rocket moves.

Principle: For every action there is an equal and opposite                  

                  reaction.

How does this friend think I got here?

Answer 4

Obviously rockets move in space.  It's the ultimate proof of Newtons Third Law, every action has an equal and opposite reaction.  The momentum of the stuff shooting out the back of the engine gives the same amount of forward thrust to the vehicle.