Semester 1 – #08 Torque & Equilibrium
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Bin Contents: a stand, the unknown mass, two 10-gram mass hangers, the clamp without bail, and two clamps with bails. |
Obtain a 1-meter long ruler – return when finished. |
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Obtain the two masses you need from your table’s drawer. |
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Weigh the ruler. |
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Weigh the clamps with bails; note that the clamp without bail is the pivot, doesn’t contribute torque, and, therefore, doesn’t need to be weighed. |
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Weigh the 10-gram mass hangers. |
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Weigh the unknown mass. |
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Slide the clamp without bail onto the ruler and set it atop the stand. Note: This experiment is a sequence of measurements that involves balancing the ruler; the images simply outline the shape of the experiment; specific known (or unknown) masses and their positions, etc, are given by the text. |
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This is exactly how the clamp without bail should be put onto the ruler and onto the stand; no other way achieves equilibrium! From this image onward, the clamp without bail will be referred to as the pivot. |
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Use the internal edge at the middle of the pivot to read its position; as shown above, the pivot is at the 52 cm mark. Note: This is actually how all of the clamps work. |
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Adjust the location of the pivot until the ruler is balanced; the pivot’s position is the ruler’s center of mass! |
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Attach the known mass to the given position. Note: The clamps with bails are attached “up-side-down” as shown. |
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Attach the unknown mass to the other side of the ruler; shift the position of the unknown mass until the system is at equilibrium. |
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Note: Keep the objects from swinging as that adds extra forces and torques. |
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Keep the known mass at the given position BUT remove the unknown mass. Loosen the pivot; slide the ruler about the pivot until you achieve equilibrium. |
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For this situation, the ruler’s own mass exerts a torque that balances the torque generated by the known mass . |
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Attach another known mass at another given position onto the ruler. Slide the ruler around the pivot until you achieve equilibrium. |
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For this situation, the torques generated by the known masses and the torque exerted by the ruler’s own weight all balance. |