How does a rocket work in a vacuum

[LibreEnergia]

Hi Brad

I still don't have an answer.   I have been told  that F=MA and Carroll and NASA say F=MV in space. NASA do not  say F=MA in a vacuum like everyone else here is saying, NASA says F=MV  https://www.nasa.gov/pdf/153415main_Rockets_How_Rockets_Work.pdf  and then NASA make the bold statement "In real rocket science, many other things also come into play" I have no idea what that statement means and I have no data to model this against.   I think we all fully understand F=MA when we are in the presence of an atmosphere or firing a rocket on the ground with earth to push against but I don't understand how we move from F=MA to F=MV, especially when we have no atmosphere and still have the force of gravity to contend with. 

Have a look carefully at how they state F = MV.  You'll note it is actually written F = M (exit) * V (exit).  They are measuring those quantities as the velocity of the exiting gasses relative to the frame of the rocket.  The mass is being accelerated from  zero to V(exit), so the relationship F = MA is what is providing the thrust. 

It just so happens that the mass flow rate MV is equivalent to MA in this situation since the initial velocity of the accelerated mass is zero.

[Nink]

I would suggest you simply buy a toy water rocket and you would quickly understand that a rocket works from ejecting mass.
If you pump it up with only air it will not work well, but fill it with water (larger mass) and then some air and it works very well.

http://www.ebay.com/itm/Toysmith-Water-Rocket-also-includes-2-Fuel-Funnels-and-Launcher-New-/331413428205?hash=item4d29c797ed:g:WB4AAOSwpDdU7ASb

LOL now if I can just get into space in the absence of gravity and atmosphere to test how it works.

[lumen]

LOL now if I can just get into space in the absence of gravity and atmosphere to test how it works.

Or if you could reason that the exiting air would push against the atmosphere as well or better than the water and yet the heavier water works better than air, you could understand that it is in fact the exiting mass that causes acceleration and not the fact that it is pushing on the atmosphere.

[LibreEnergia]

LOL now if I can just get into space in the absence of gravity and atmosphere to test how it works.

Think about a jet boat. They work much better when the jet is exhausted above rather than into the water. If it needed to 'push' on something other than the ejected mass itself this would not be the case.

[Nink]

Think about a jet boat. They work much better when the jet is exhausted above rather than into the water. If it needed to 'push' on something other than the ejected mass itself this would not be the case.

A jet boat has an unlimited supply of water that it draws from underneath the boat.  It then uses Newtons 3rd law of motion by ejecting the water (equal and opposite reaction)  to travel horizontally across  the force of gravity. The water goes one way the boat goes the other. I get it.   

Unfortunately a rocket does not have an unlimited supply of water or fuel or anything to push away from itself to invoke 3rd law of motion and it also has to travel vertically straight up against the force of gravity and not horizontally across the force of gravity. A rocket has a limited  supply of fuel it can burn to generate thrust and that fuel is quickly exhausted. By the time the rocket reaches 100km (if it even reaches that height) and the multiple stages of the rocket that contain the fuel have been exhausted and separated from the rest of the rocket and now with out fuel to push out I still have no idea how it travels the next 60km straight up into space.

As I continue to state everyone has great theories but that is all they are, theories and a theory needs to be proven.

This is basic high school physics. Although NASA may say Don't worry this is rocket science we can quickly verify the facts with data.  WE NEED THE DATA and without the data we are just making stuff up.