# Can thrust occur with constant mass?

I understand that in the case of a spacecraft, thrust works by releasing fuel with a velocity in one direction, pushing the rocket in the other direction. This is shown by the equality mv=mv.

Now. If let's say I somehow am in space, could I move by simply thrusting my hips/legs back and forth even though there is no exchange of mass (like fuel in rockets)?

• – sammy gerbil Mar 21 '18 at 20:31