Hi there, quick question:
How would you find the shear modulus of a ruler (plastic 12 in)? I don't exactly get it. You have to bend it which will help you...???
Bending it like a beam, or measuring its vibrational frequency when clamped at one end, will tell you the bulk modulus E, not the shear modulus G. For a shear modulus determination, you would have to twist it in torsional loading. Then look up the equation for twist angle vs torsional stress. The section moment of inertia and the shear modulus will be involved.