Okay, so my professor messed up on this problem. For part B, use the shear modul

Question

Okay, so my professor messed up on this problem. For part B, use the shear modulus for copper again, not lead. She forgot to change it.

A copper cube measures 5.48cm on each side. The bottom face is held in place by very strong glue to a flat horizontal surface, while a horizontal force F is applied to the upper face parallel to one of the edges.

I already did Part A.

A.) How large must F be to cause the cube to deform by 0.17mm ? F = 4.1*105N

B.) If the same experiment were performed on a lead cube of the same size as the copper one, by what distance would it deform for the same force as in part B? ( Again, use the shear modulus for copper, not lead.)

Explanation / Answer

Shear modulus, G = F*l/(A*delx)

A = 0.0548*0.0548 = 3.00304*10^-3 m^2

l = 0.0548 m,

for lead, G= 5.6*10^9 Pa = 44.7*10^9 N/m^2

F = 4.1*105N

So, 5.6*10^9 = (4.1*105 *0.0548)/(3.00304*10^-3 * delx)

So, delx = 1.336*10^-3 m = 1.336 mm

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