Thermodynamics
> Heat and the First Law > Heat Capacity
DCS#
3A70.20
RUCHHARDT'S APPARATUS
APPARATUS
10.4
L flask with glass tube
105-48-C
stopwatch
105-48-C
steel ball
105-48-C
chamois
105-48-C
alcohol
105A
magnet on a string
DESCRIPTION
The ball just barely fits inside the precision
bored glass tube and, when dropped into the tube, will oscillate on a cushion
of trapped air. The period of oscillation of the ball can be used
to determine the ratio of specific heats, cp/cv,
of the air inside.
NOTES
cp/cv = 4p2mV/(A2PT2)
where m = mass of ball
volume of air, V = 10.4 l
cross sectional area of tube, A = 2.0x10-4
m2
P = atmospheric pressure
Use chamois and alcohol to clean inside of
glass tube before use.
Use a level to make sure that the tube is vertical.
There is a rubber mat inside flask to protect
it when the ball drops. Use the magnet to retrieve the ball or remove
the stopper from the bottom of the flask.
