A polystyrene component must not fail when a tensile stress of 1.25 MPa (180 psi) is applied. Determine the maximum allowable su
rface crack length if the surface energy of polystyrene is 0.50 J/m2 (2.86 103 in.-lbf/in.2 ). Assume a modulus of elasticity of 3.0 GPa (0.435 106 psi).
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Answer:
<h2>36cm from the surface</h2>Explanation:
Equation of refraction of a lens is expression according to the formula given below;
R is the radius of curvature of the convex refracting surface = 12cm
v is the image distance from the refracting surface
u is the object distance from the refracting surface
n₁ and n₂ are the refractive indices of air and the medium respectively
Given parameters
R = 12 cm
u = (since light incident is parallel to the axis)
n₁ = 1
n₂ = 1.5
Required
<em>focus point of the light that is incident and parallel to the central axis (v)</em>
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Substituting this values into the given formula we will have;
Cross multiply
Hence Light incident parallel to the central axis is focused at a point 36cm from the surface