How intuitive are you?
Physics is the study of how things in our universe work. There was once a man named Isaac Newton. He came up with three laws: An object in motion stays in motion and an object at rest stays at rest unless acted upon by another force. That is why balls stop rolling in Earth. If there was no friction, gravity, or object to stop the ball, it would continue rolling forever.
The second law is: force= mass x acceleration. That means that the more mass that an object has and the speed in which it is accelerating result in the force that it will hit another object with. The third law is: for every action, there is an equal and opposite reaction. That means that if a person runs into a rolling chair, the equal action will be the chair rolling forward and the opposite action will be the person stumbling backwards.