PASCO ME-9341 INTRODUCTORY ROTATIONAL APPARATUS - Manual (Page 27)

012-03051F Introductory Rotational Apparatus
23
Exp 1 – Angular Acceleration - 1
Teacher's Guide
Introduction
Applying torque with a spring balance ensures that the applied force is simple to understand, as opposed to using a
falling mass, as in Experiment 2. The disadvantage is the inherent inaccuracy of using a hand-pulled device.
Students measure the force and the torque arm, each of which can be independently varied, so the effects of each
on acceleration can be examined. Moment of inertia can also be qualitatively investigated, yielding relative
values.
Alternatives
➀ Larger forces than those listed in the lab sheet can be used. However, the speeds increase and the difficulty in
maintaining a constant torque also increases.
➁ For a shorter lab period, all students could do steps 1-7. The class can then be split into three groups to carry
out steps 8, 9, and 10.
Notes – on Procedure
➂ For best results on all of these labs, use a fine thread and make sure that the thread is wound evenly around the
spindle without overlapping.
➃ It is difficult to maintain a constant
force on the string. We found that
the best results were obtained when
the data was taken for a short time
(about 1 second) rather than for the
entire length of the string.
➇ The larger spindles are proportion-
ally more difficult to maintain at a
constant force, due to the higher ac-
celeration.
➈ The higher forces are also harder to
maintain, for the same reason.
average
Object Force (N) R (m) alpha (rad/s/s)
base plate: 0.4000 0.0150 0.9724
1.0000 0.0150 2.3181
2.0000 0.0150 4.5086
0.4000 0.0200 1.5984
1.0000 0.0200 2.7110
0.4000 0.0250 1.5645
1.0000 0.0250 3.7425
B.P. + ring 0.4000 0.0150 0.8913
1.0000 0.0150 1.7716
1.8000 0.0150 2.9834
2.0000 0.0150 3.2425
B.P. + disk 0.4000 0.0150 0.5763
1.0000 0.0150 1.2496
2.0000 0.0150 2.0803
B.P. + bar 0.4000 0.0150 0.7808
1.0000 0.0150 1.5346
2.0000 0.0150 3.7007