The ballistic pendulum is easy to use and understand. It provides a classic demonstration of inelastic collsions, the conservation of momentum, and projectile motion.
This durable, inexpensive unit uses a lightweight nylon carriage/ball-catcher that swings freely on its suspension lines to push a counter weighted indicator needle, giving the angle of highest ascent. The needle remains in place at the height of the arc, opposite a scale marked in degrees.
The base and the pendulum have leveling screws. Has an adjustable, self locking, spring loaded gun. Comes complete with instructions.