# Mass in deep space

I get so confused how mass works in space. I know these may sound like stupid questions but I've never had anyone answer them before. First if you're flying a spacecraft around in space. What role does mass play if you're weightles?
For example why couldn't you hit the gas and indefinitely accelerate to however fast you wanted to go?
I guess another question is in space what forces act on mass if there is no friction wind resistance or gravity? Is there a good link to a website that explores these questions?

Mech_Engineer
Gold Member
Regardless of whether a spacecraft (or any object) is in a gravity field, it is subject to inertia which is in turn a primary manifestation of mass. It is inertia which prevents infinite acceleration, not gravity. See here:

https://en.wikipedia.org/wiki/Inertia

Wikipedia.org said:
Inertia is the resistance of any physical object to any change in its state of motion (this includes changes to its speed, direction or state of rest). It is the tendency of objects to keep moving in a straight line at constant velocity.
...
Inertia is one of the primary manifestations of mass, which is a quantitative property of physical systems. Isaac Newton defined inertia as his first law in his Philosophiæ Naturalis Principia Mathematica...

PeroK