Students will observe "explosions," in which one student on a dynamics cart pushes another. From this, they will confirm the relationship between mass and velocity in determining momentum. They will also reinforce the idea of a closed system by experimenting with which student provides the pushing force. Then a single student on a cart will participate in inelastic and elastic collisions with a thrown weight. Students will observe that a faster throwing speed results in a faster cart speed for both collision types. They will also observe that more force is imparted to the objects in elastic collisions, and make conclusions about technological design based on that observation.