A simple and easy to use kit for work on momentum collisions and the coefficient of restitution as well as conservation of energy.The kit consists two bogies having one side with Hook & Loop pad and other side with spring.The collision track measures 1.2M in length and is graduated.It includes:A pair of support feet 2 photogate support holders and rods (photogates are not included)Masses set of 50 g 20 g and 10 g each.Not for friction free work.