If there is no outside force acting on an object that is in motion, can its motion change? Will it stop? Explain your answer.

yes for both.

Explanation:

according to Newton's first law an object in motion will stay in motion until acted on by an outside force and an object at rest will stay at rest until acted on by an outside force. this means that an object that is moving will stay moving in the direction that it's moving and at the same speed unless there's an outside force acting on it and it will keep in motion until there is an outside force acting on it.

The motion can change and it also can stop from gravitational force