PASCO ME-9833 Physical Pendulum Set User Manual
Page 10
®
Model No. ME-9833
Physical Pendulum Set
10
1.Repeat the procedure for the other two ‘legs’ of the irregular shape. Determine whether or not the
moment of inertia about the parallel axis (the pivot point) is equal to the sum of the moment of
inertia about the center of mass plus ML
2
cm
.
2.Repeat the procedure for another physical pendulum object, such as the solid disk.
Measurements and Calculations
Questions
1. How does the value of the moment of inertia about the pivot point compare to the sum of the
moment of inertia about the center of gravity I
cg
plus ML
2
cg
?
2. Do your results confirm the parallel axis theorem? Why or why not?
3. How do you know that the center hole is the center of gravity?
Table 1: Parallel Axis Theorem for Irregular Shape
Item (units)
1
2
3
Object
irregular shape
Mass of object, M (kg)
Step diameter (m)
Step radius, r (m)
Mass of hanger, m (kg)
α
cg
, avg. angular acceleration
cg
(rad/s
2
)
τ
cg
, torque, rm(g - r
α
cg
) (N m)
I
cg
, moment of inertia (kg m
2
)
L
cg
, distance - pivot to center of gravity (m)
ML
2
cg
, moment of inertia, parallel axis (kg m
2
)
I
cg
+ ML
2
cg
(kg m
2
)
α
pivot
, avg. angular acceleration
pivot
(rad/s
2
)
τ
pivot
, torque, rm(g - r
α
pivot
) (N m)
I
pivot
, moment of inertia, pivot point (kg m
2
)
Percent difference, I
pivot
and I
cg
+ ML
2
cg