Hi everyone, just some quick background information, I'm only in grade 9 so I'm not the brightest in physics as of yet however I know some information here and there. My question is about the Law of Inertia (Newton's first law). The law states that an object basically remains in motion unless acted upon by an external unbalanced force. So does this mean that say if I threw a rock in space which is a near vacuum, the rock should theoretically move forever with a constant velocity, is this correct? If so, if I hit the moving rock, would the force add on top of the original force moving the rock or would the original force be "gone" and the rock would move with the new force? Sorry if I worded this in a confusing way or if I posted this in the wrong forum. But thanks in advance to anyone willing to answer/ clarify!