PASCO ME-9502 Statics System - Manual (Page 31)

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M o d e l N o . M E - 9 5 0 2 E x p . 5 A : C e n t e r o f M a s s
0 1 2 - 1 2 8 7 6 B 27
• Recalculate the torques about the pivot point.
5. Are the torques balanced?
Asymmetrical Plate
Replace the Balance Arm with the Force Sensor Mount. Hang the Asymmetri-
cal Plate from the rod on the Force Sensor Mount.
Since the force of the rod acting on the plate is the equilibriant to the sum of the
gravitational forces acting on the plate, the line of force exerted by the rod must
pass through the center of the mass of the plate. Loop a piece of thread over the
rod and attach a mass hanger to the end of the thread.
Use a pencil or a “dry erase” pen to draw a line on the Asymmetrical Plate that
marks the position of the thread on the plate.
Remove the thread and mass hanger. Hang the plate from a different hole. Put
the thread and mass hanger back on the rod. Draw a new line on the plate that
marks the position of the thread.
Repeat the process for a third different hole. Draw a third line on the plate.
6. Does the line showing where the thread is hanging pass through the center
of mass of the plate?
7. Would this method work for a three dimensional object? Why or why not?
Extension
Remove the thread and plate from the rod. Try to balance the Asymmetrical Plate on your finger by placing the tip
of you finger under the point where the three drawn lines intersect. What happens?
Position Force (F = mg) Torque (  = F d)
2
3
Mass
hanger
Asymmetrical
Plate
Force Sensor
Mount
Thread
Rod
Figure 5.3: Finding the
Center of Mass