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1. A laboratory balance essentially uses the method of moments to compare an unk

ID: 2236645 • Letter: 1

Question


1. A laboratory balance essentially uses the method of moments to compare an unknown mass with a known mass. Some balances have constant and equal lever arms, and others do not. Figure 4(a) shows the balance used in our lab. Its sketch diagram is shown in fig.4 (b), where m1 is the unknown mass, m2 is the known mass and mc is the mass of the metal scale bar.


(a) Explain how the condition (the sum F=0 ) is satisfied for the balance in fig.4 (b).


(b) Explain how the condition (the sum of torques = 0) is satisfied for the balance in fig.4 (b). the torques are calculated about the rotating axis through the pivot point O.




2. Does the individual torque depend on the position of the rotating axis? Does the second equilibrium condition (sum of torque = 0) of a rigid body depend on the position of the rotating axis? Why?

Explanation / Answer

I think this should be in the advanced section.