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Instruction Manual
Manual No. 012-08251A
ROTATIONAL
INERTIA SET
Model No. ME-9774
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Model No. ME-9774 ROTATIONAL INERTIA SET
ROTATIONAL INERTIA SET
Model No. ME-9774
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*Use Replacement Model Numbers to expedite replacement orders.
What’s included:
1) Release
2) Large Solid Sphere (Diameter = 10cm; Mass = 810g)
3) Small Solid Sphere (Diameter = 5cm; Mass = 110g)
4) Large Disk (Diameter = 10cm; Mass = 370g)
Part No.
648-08194
699-143
699-142
648-08193
5) Small Disk (Diameter = 5cm; Mass = 70g)
6) Large Ring (Diameter = 10cm; Mass = 230g)
7) Small Ring (Diameter = 5cm; Mass = 90g)
648-08192
648-08191
648-08190
Introduction:
The Rotational Inertia Set includes two solid spheres, two solid disks, two rings, and
a release mechanism. There is a large set of a sphere, disk, and ring, all having the
same radius and there is a small set of a sphere, disk, and ring, all having the same
radius. These objects are designed to be used to demonstrate the difference in
rotational inertia of different shaped objects.
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ROTATIONAL INERTIA SET Model No. ME-9774
Suggested Demonstration:
Set two objects (i.e., the ring and the disk of same radius) at the top of an inclined
ramp. Use the straight side of the release mechanism to hold the objects in place on
the ramp (see Figure 1). This will allow you to release both objects from rest at the
same time in the same position. Ask the students which object will reach the bottom
of the ramp first. Release the objects by pulling the release mechanism away from
the objects.
When using two objects of different radii (i.e., the small disk and the large disk), use
the stepped end of the release mechanism to hold the objects at the same starting
position (see Figure 2).
Note that the results are not affected by the mass or radius of the object. The shape
or distribution of the mass determines the outcome. The sphere will reach the
bottom first, followed by the disk, and the ring will be last.
An interesting addition to this demonstration is to compare a Dynamics Cart with the
sphere. The Dynamics Cart will win the race with the sphere because the cart has
very little mass that is rotating.
Fig. 1
Fig. 2
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