What would happen if a cannon ball was fired at 50 mph on the truck in the same direction as the truck while the truck is also going 50 mph

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

At the negative terminal of the battery the electron has electric potential energy. what happens to this energy as the electron jumps from the negative to the positive terminal?

What quantity do units represent in value