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1.

Determine the coordinates of the centroid of the bearrTs cross-sectional area shown in the figurę. Consider the size of the comer welds at A and B for the calculation to be negligible.

1.

150 mm--\

A.    y    =    172mm from the    top

B.    y    =    185mm from the    top|

C.    y    =    154mm from the    top

D.    y    =    145mm from the    top

E.    y    =    166mm from the    top

Solution

The correct answer is C.

The y-axis is an axis of symmetry and the centroid must lie on this axis. Thus, x = 0.

Centroidal y-coordinate:

^ y i • Ai = 7.5 • 15 • 150 + 90 • 150 • 15 + 215 • n • 50² = l,907,981.05?m?i³

= l54mm from the top

y =

^ A_t = 15 • 150 + 150 • 15 + TT • 50² = 12,353.98mm³ _ E 9 i' A i

E Ai