PASCO ME-9833 Physical Pendulum Set User Manual

Page 8

Model No. ME-9833

Physical Pendulum Set

6. Put the object to be measured onto the shaft

of the sensor above the three step pulley.
Secure it in place with one of the mounting
screws.

7. Measure and record the mass, m, of a mass

hanger.

8. Attach the mass hanger to the end of the

string that is draped over the Super Pulley.

Data Recording: Center of Gravity

1. Wind the string about the step pulley so that

the mass hanger is just below the Super Pulley.
Hold the irregular shape in place.

2. Start recording data and then release the

irregular shape so that it rotates freely.

3. Stop recording data when the mass hanger

reaches its lowest point.

4. Repeat the process a total of three times.

Analysis: Center of Gravity
Find the moment of inertia about the center of gravity.

1. Set up a graph display in the software of angular velocity versus time.

2. Select a region of the first run of angular velocity data and select ‘Linear Fit’ from the

‘Fit’ menu.

3. Record the value of the slope as the first value of angular acceleration around the center

of gravity.

4. Repeat the process for the other two runs of data.

5. Find the average angular acceleration,

, and record it in the data table.

6. Calculate the net torque,

τ = rm(g - rα). Calculate the moment of inertia about the center

of gravity by dividing the net torque by the average angular acceleration. Record the result
as the moment of inertia about the center of gravity, I

. (

)

Equipment Setup: Parallel Axis

1. Temporarily remove the irregular shape from the top of the Rotary Motion Sensor.

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Figure 1-1: Irregular shape
mounted on the RMS at
the center of gravity

Mounting screw