PASCO ME-8950A COMPLETE ROTATIONAL SYSTEM - Manual (Page 31)

012-05293F Complete Rotational System
27
center post string
stop screws (2)
Procedure
1. Select ’Smart Pulley (Rotational)’ as the type of sensor. Set up a Graph display of Velocity (rad/s)
versus time.
2. Hold the string just above the center post. With the square mass against the outer stop, give the
track a spin using your hand.
3. Click ’Start’ to begin recording data. After about 20 data points have been taken, pull up on the
string to cause the square mass to slide from the outer stop to the inner stop.
4. Continue to hold the string up and take about 20 data points after pulling up on the string. Click
’Stop’ to end recording data.
5. Examine the Graph display of Velocity (rad/s) versus time.
The graph shows the angular speed before and after the
square mass is pulled toward the inner stop. Rescale the
graph if necessary.
6. Use the Smart Cursor tool to determine the angular speed
immediately before and immediately after pulling the
string. Record these values in Table 4.1.
7. Repeat the experiment a total of three times with different
initial angular speeds. Record these values in Table 4.1.
Part II: Determining the Rotational Inertia
Measure the rotational inertia of the apparatus twice: once with the square mass in its initial
position and once with it in its final position.
Setup
1. Attach a Photogate with Pulley to a mounting rod and attach the mounting rod to the black sup-
port rod on the base.
2. Wind a thread around the pulley on the center shaft and pass the thread over the Pulley. See Fig-
ure 4.3.
Trial Number
Angular Speeds
1
2
3
Initial Final
Table 4.1: Data
Figure 4.3: Set-up for determining rotational inertia
300g mass
"A" base
rotating
platform
hanging mass
10-spoke pulley with
photogate head