Question

A bar of cross section A is subjected to equal and opposite tensile force F at its ends. If there is a plane through the bar making an angle Q, with the plane at right angles to the bar in the figure 

a) Find the tensile stress at this plane in terms of F, A and Q 

b) What is the shearing stress at the plane in terms of F, and Q. 

c) For what value of Q is tensile stress a maximum.

Answer 1

1) Tensile stress = Normal force/Area

Normal force = F cosθ

Comments

Why is the area A/cos(theta)

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Area A/Cos(theta) because A is the area of vertical part but we want the area of the inclined part which forms a triangle