PURPOSE: To determine the speed of a B-B using rotational kinematics.

DESCRIPTION: A B-B is shot from the air gun with a linear velocity v, such that it passes between the two rotating discs which have a separation d and are rotating with an angular velocity w. The angle a that the two discs rotate while the B-B is traveling between them is determined by inspecting the two discs. The velocity of the B-B is then determined by using the relation: v = w d / a. In this case the angular velocity w of the rotating discs is 1800 rpm, and the distance d between the discs is 1 meter.

SUGGESTIONS: CAUTION: Lift apparatus by handles only. DANGER: Gun can be very dangerous. Pump just before firing to assure uniform velocity for several trials.

REFERENCES: (PIRA unknown.) See also Demonstrations C7-51: BALLISTIC PENDULUM - PELLET GUN and C7-53: AIR TRACK - SPEED OF AIR GUN PELLET for other ways to determine the B-B velocity.

EQUIPMENT: B-B gun with B-Bs (from air track in room 0402), disc rotating mechanism with paper discs, and backstop.

SETUP TIME: 15 min.