This ballistic pendulum tester consists of a spring gun that fires a steel ball into a suspended nylon pendulum bob with a rubber insert. The pendulum bob swings away and its highest position reached is marked by a counter-weighted needle that remains in place at the height of the arc. The laws of conservation of energy and momentum for the inelastic collision of the steel ball with the pendulum bob are used to calculate the velocity of the ball as fired by the gun from the data of the height of rise of the bob and the mass of the ball and the bob.
The pendulum bob is then moved out of the way so the gun can fire across the room. The laws of ballistics are used to calculate the spot on the floor the ball will hit, and a metal pail can be placed on the predicted spot to catch the ball.
Both pendulum and base have leveling screws. The spring-loaded gun has a self-locking trigger and rubber bumper to prevent damage on impact.
This Ballistic Pendulum is definitely better made than others on the market. Rather than a flimsy composite wood construction it is primarily made from sheet metal which has been formed for stiffness. I have some hope that it will actually last a decent amount of time in my class room.