A pair of carts, especially designed single piece moulded plastic body of unbreakable ABS. These unique precision Dynamics Carts are new improved design of the old dynamic trolleys, conventional type, used in most schools and colleges for experiments in motion. These carts are rigid and strong enough to take the weight of an adult without bending or breaking and can easily with stand routine rough usage or fall from workbench etc. Plastic body mounted on a set of 3 low-friction wheels providing straight motion over long distances. A lockable spring-loaded exploder plunger has 2 levels of spring compression and is activated by a trigger knob on top of the trolley. A cushioned surface mounted on top of each cart enables placing of additional masses for increasing the effective weight of the cart. The carts can also be stacked on top of each other to make its effective mass 2-3 times its basic mass. Velcro pasted at the back end of each cart enables the study if inelastic collisions.