An object in motion will stay in motion until when a) until a balanced force acts on it b) until an unbalanced force acts on it c) no matter what d) until a force in equilibrium acts on it

Johnny rode his bike 4 blicks down the street to his friend's house once he got to his friend house and realized he could not cone out to play he turned aroubd and went back home.what is displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point