PASCO ME-9341 INTRODUCTORY ROTATIONAL APPARATUS - Manual (Page 28)

Introductory Rotational Apparatus 012-03051F
24
Acceleration vs. Force
Radius = 1.5 cm
●
●
●
❍
❍
❍
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Angular Acceleration
Applied Force
Base plate alone
With added disk
Ranking the three objects in increasing order of inertia would give: ring, bar, then disk. This is misleading,
because for objects of the same mass and radius the ring would have the highest inertia. The lower inertia of the
ring is due to its smaller radius, not its shape.
Using the spring scale as a constant-force apparatus is good in a way because it allows the student to directly see
that the acceleration is proportional to the force, without messing around with the falling masses as in experiment
2. Its accuracy is limited, however, by the difficulty in maintaining a constant force on the scale. For this reason, I
would consider experiment 2 to be preferable to experiment 1 for anything but the most basic introductory course.
The acceleration is directly proportional to the
force for a constant radius.
Increasing the mass by adding another disk
increased the rotational inertia and decreased
the acceleration.
Notes – on Analysis
The acceleration is directly propor-
tional to the radius for a constant
force.
●
●
●
0
0.5
1
1.5
2
2.5
3
3.5
4
0 0.005 0.01 0.015 0.02 0.025 0.03
Angular Acceleration
Radius
Acceleration vs. Radius
Force = 1.0 N
Acceleration vs. Force
Radius = 1.5 cm
Acceleration vs. Radius
Force = 1.0 N