PASCO ME-8950A COMPLETE ROTATIONAL SYSTEM - Manual (Page 42)

Complete Rotational System 012-05293F
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Applying Newton’s Second Law for the hanging mass, m, gives (See Figure 6.1)
Solving for the tension in the thread gives:
Once the linear acceleration of the mass (m) is determined, the torque and the angular
acceleration can be obtained for the calculation of the rotational inertia.
Setup
1. Set up the Rotational Accessory as shown in Figure 6.2. Mount the disk with its bearing side up.
Use the platform adapter to fasten the disk to the track at a large radius.
2. Mount two square masses on the opposite end of the platform to act as a counterweight. Be sure
to tighten the screws.
3. Mount the Photogate/Pulley System to the base and connect it to an interface.
4. Run the DataStudio program.
Measurements For the Theoretical Rotational Inertia
Record these measurements in Table 6.1.
1. Weigh the disk to find the mass M.
2. Measure the diameter and calculate the radius R.
3. Measure the distance, d, from the axis of rotation to the center of the disk.
ΣF
mg T – ma = =
T m g a –
( )
=
rotating
platform
hanging
mass
"A" base
hanging
mass
mg
T
a
rotational disk
rotating plat-
form
platform
adapter
Figure 6.1: Rotational Apparatus and Free-Body Diagram
Figure 6.2: Set-up for Disk Off-Axis
rotational disk
platform
adapter
"A" base
10-spoke pulley with
photogate head