i am a second year civil engineering student, in mechanics of materials we are dealing with twisting and bending moments and our professor has asked us to think up an experiment in which we can "find" the 1st moment of area of different shapes(adsbygoogle = window.adsbygoogle || []).push({});

this is my idea so far but i need some help developing it

i know that when a beam is subjected to transverse loading, the shear stress in the beam is t=VQ/(Ib) therefore

Q=t*I*b/V

now I, b and V are easy to measure, the problem is finding t (the shearing stress)

what i have thought of doing is using strain gages, stick them at a point at which i know the internal shearing stress V, but im not quite sure how to measure the SHEARING stress using the strain gage, had it been the normal stress i could have used youngs modulus to find the stress through the normal strain, or using a strain rosette(dont think its necessary)

can anyone improve on this or even think of a better way- it doesnt necessarily need to have anything to do with bending and twisting.

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# Homework Help: Finding 1st moment of area

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