Ballistic Pendulum and Projectile Motion

PHY 200 & 230

Based on Loyd #13. Students will use a ballistic pendulum apparatus to determine the initial velocity of a projectile just as it leaves a gun. There are two different experiments conducted separately seeking agreement as to the initial velocity of the same metal ball. In one case, the ball will be launched and captured by a stationary pendulum which receives momentum and swings upward as a result. Later, the pendulum is taken away and the same projectile is fired horizontally out into free air space and allowed to fall to the floor. Conservation of momentum and conservation of energy principles allow for the calculation of velocity given measurement of the masses and distances involved.

Equipment

Notes

This apparatus costs nearly $1000 to replace. Find appropriate wrenches and other tools to service, and as always, don't experiment with repair techniques. Consult supervisor when uncertain.

Aim toward center of room. Ensure/test that the pendulum will catch the ball and be caught on the quantized ramp at least once in every three shots. Never remove nor swap pendula. See that set screws are slightly less than snug so pendulum swings freely while locknuts are tight to maintain. Use wrenches (not pliers) on lock-nuts and set screws. Spring metal tab catch on some pendula must be depressed inward to release ball, not bent outward.

With pendulum up on the ramp out of the way, ball should fly freely out into only air. If ball strikes ramp support, rotate gun rod about 90 degrees at a time until it doesnt. Never attempt to bend rods to achieve alignment. Most parts are pinned in place at the factory so they cannot be removed nor shift in position even after loosening screws/nuts/bolts, so please don't try.

Place large wooden boards at the aisle end of each lab bench for projectiles to bounce into after hitting the floor. Place one sheet of carbon paper on each table.

Make sure that the room has plenty of paper.