The trolley physics experiment is a practical experiment that is often used in a physics lesson to demonstrate force, momentum, and mass. The trolley is a horizontal metal track on which a sturdy metal trolley is balanced. By rolling objects of different masses or weights along the track, the student can demonstrate how forces act upon the trolley. This experiment is ideal for teaching the basics of mechanics and motion, particularly the idea of a balanced system. It can also demonstrate the relationship between mass, force, and momentum. It is an ideal way to introduce pupils to fundamental ideas about forces and motion.