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Ballistic Pendulum


Consists of a spring-loaded mechanism that fires a brass ball, a pendulum, and a curved scale. The pendulum has a catching mechanism which catches the brass ball, and a ratchet on the bottom. When the pendulum catches the ball it starts the end of it starts travelling along the curved scale. The ratchet on the bottom of the pendulum only allows the pendulum to progress one way up the scale, causing it to come to a standstill as soon as it starts swinging back towards the starting position.


  • To demonstrate the usage of a ballistic pendulum in measuring the velocity of a projectile
  • To demonstrate a nearly-perfectly-inelastic collision.


  • Ballistic pendulum


  1. Start by removing the brass ball from the pendulum and placing it on the end of the firing mechanism.
  2. Push the firing mechanism in by the brass ball until the trigger engages with the firing mechanism. At this point if you stop pushing on the brass ball, it shouldn't pop back out. (You may want to raise the pendulum out of the way during this step.)
  3. Make sure the pendulum is at rest at the lowest part of it's swing.
  4. Pull the trigger on the firing mechanism.
  5. Observe the height that the ballistic pendulum reached.


If you want to perform an actual measurement of the kinetic energy or velocity of the ball, this can be done too. The mass of the ball and the mass of the pendulum are noted on the base of the demo. The only detail you need in addition to that is the height of the scale relative to the resting height of the pendulum, since the scale starts from zero.

Wikipedia Article on Ballistic Pendulum:

Demo room information

Location LMN0
Maker Unknown
Current State Working
demonstrations/1_mechanics/1m_work_and_energy/ballistic_pendulum/start.txt · Last modified: 2020/01/29 17:44 by demoroom