Question

1. how can you know when an object has an unbalanced force on it?

Explanation:

According to Newton's first law of motion, an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. So, if an object's velocity (speed and/or direction) changes, there is an unbalanced force acting on it.

Answer:

If an object's velocity (speed and/or direction) changes, there is an unbalanced force acting on it.