The aluminum rod (E_1 = 75 GPa) is reinforced with the firmly bonded steel tube (E_2 = 209 GPa). The diameter of the aluminum rod is d = 28 mm and the outside diameter of the steel tube is D = 42 mm. The length of the composite column is L = 729 mm. A force P is applied at the top surface, distributed across both the rod and tube. Determine the normal stress sigma in the aluminum rod when P = 97 kN:

its a 5.5 n

glad that

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.