# A question about thrust VS mass

1. Jul 8, 2008

### DarkElfa

I've always wondered about something. If there is no gravity or resistance in space, than why does it take more thrust to move a 1 ton object than a 1 pound object. Shouldn't thy both both be equally easy to move since neither has any weight in space?

2. Jul 8, 2008

### mathman

Even though they may be weightless, they still have mass. Newton's third law is F=ma, therefore to accelerate the same amount, a more massive object requires more thrust (force).

3. Jul 9, 2008

### DarkElfa

Why does mass matter if it doesn't have weight?

4. Jul 9, 2008

### LURCH

Mass is the resistance to acceleration. Weight is only the way in which gravity effects (and is effected by) mass, but mass resists acceleration whether there is gravity or not.

Also, the same amount of force will move a 1-pound object and[i/] a 1-ton object in space; it just won't move the 1-ton object nearly as fast.

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