PASCO ME-9833 Physical Pendulum Set User Manual

Page 19

Physical Pendulum Set

Model No. ME-9833

Experiment 4: Use a Physical Pendulum to Measure the
Acceleration Due to Gravity, g

The purpose of this experiment is to use a physical pendulum to measure the acceleration due to
gravity.
Equipment

Background Information

For small amplitudes of oscillation, the motion of a physical pendulum is approximately ‘simple
harmonic motion’ and its theoretical period of oscillation, T, is given by

where I

pivot

is the moment of inertia of the physical pendulum about its pivot point, M is the mass

of the pendulum, and L

is the distance from the pivot point to the center of gravity. The Parallel

Axis Theorem states that the moment of inertia about the pivot point, I

pivot

, is the sum of the

moment of inertia about the center of gravity, I

, and the moment of inertia of the pendulum as if

all the mass is concentrated at the center of gravity. The period, T, is then given by

For a physical pendulum such as the 28-cm Pendulum Bar, the moment of inertia about the center
of gravity is very close to

where “a” is the length of the physical pendulum and

“b” is the width.
Solving for g gives

Item

PASCO Interface and DataStudio software

Balance

Rotary Motion Sensor

Vernier caliper

Physical Pendulum Set

Base and Support Rod

pivot

MgL

------------------

MgL

-------------------------------

------M a

(

)

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