ballistic pendulum
Date: circa 1980
Inventory Number: 2006-1-0078
Classification: Demonstration Device
Subject:
User: Department of Physics, Harvard University (founded 1884)
Cultural Region:
Place of Origin:
Dimensions:
21 × 11.5 × 16.3 cm (8 1/4 × 4 1/2 × 6 7/16 in.)
Description:
Ballistic pendulum. Painted cylinder, most likely made of wood and filled with clay, sand, or some other material. The filling gives it considerable weight. On top and bottom are caps of wood ringed with brass. Caps are fastened to device with L-shaped slots on the brass rings into which fit pegs and screws distributed around the circumference of the cylinder. Nuts on the screws hold the cap. The cylinder is most likely filled with clay, sand, or some other heavy material.
In the middle of the cylinder around the circumference are four slotted-head screws. On one side of the cylinder toward each end are metal strips fastened by four screws. Each strip has a brass rod soldered on perpendicularly. It also has two pieces with holes by which the device may be hung.
In the middle of the cylinder around the circumference are four slotted-head screws. On one side of the cylinder toward each end are metal strips fastened by four screws. Each strip has a brass rod soldered on perpendicularly. It also has two pieces with holes by which the device may be hung.
Signedunsigned
Inscribedhandwritten on side of cylinder: A / 8E / B
FunctionIllustration of conservation of momentum. Determining the velocity of a projectile by measuring the distance traveled by the pendulum. The pendulum would be attached to strings and filled with clay or sand. A projectile would be fired at the pendulum and transfer its momentum to it. The pendulum would move forward and up. The distance the pendulum traveled, as well as the masses of the projectile and the cylinder, would be used to calculate the initial velocity of the projectile.