1st Law of motion
I use the 1st law of motion everyday when I drive to school. I stay at a constant rate until I get to a stop sign or light. I hit the brake which changes the motion of the car.
Both people are pushing at a constant rate until an external force acts against it.
the ball is going to stay at a constant rate unless it hits something.
the box is going to stay in motion unless the man stops pushing it.
objects at rest stay at rest. objects in motion stay at motion. unless an external force acts on it.