The Area Of the Inclined Plane Affects the Stresses  
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The figure shows a prismatic bar whose right end is an inclined plane. The angle between the normal to the inclined surface and the horizontal is theta. The cross sectional area of the bar on vertical and inclined planes are shown at the bottom right for comparison. The area of the inclined surface is larger.

As the angle θ in the sketch above is rotated through positive and negative values, observe how dramatically the cross-sectional area of the inclined plane changes relative to the cross-sectional area of a vertical plane.