Find the height ȳ of the centroid of the T-section above its bottom edge.
Centroid & second moment of area worksheet with answers
A 100 mm × 240 mm plate has a circular hole of diameter 40 mm on its vertical centre line, with its centre 84 mm above the bottom edge. Find the height ȳ of the centroid above the bottom edge.
A channel section lies with its open side up: a base plate 120 mm wide with two upright legs, 100 mm high overall. Base and legs are all 12 mm thick. Find its second moment of area Ix about the horizontal axis x through its centroid.
Find the second moment of area Ix of the T-section about the horizontal axis x through its centroid.
The T-section is used as a beam with the flange on top and carries a sagging bending moment of 40 kN·m. Find the bending stress σbottom at the bottom edge.
A welded I-section has a top flange 150 × 18 mm, a web 160 mm high and 14 mm thick, and a bottom flange 180 × 12 mm (width × thickness). Find its second moment of area Ix about the horizontal axis x through its centroid.
Answer key
- 1. ȳ = 210.1 mm
- 2. ȳ = 122 mm
- 3. Ix = 3.521 × 10⁶ mm⁴
- 4. Ix = 26.37 × 10⁶ mm⁴
- 5. σbottom = 118.5 MPa
- 6. Ix = 41.82 × 10⁶ mm⁴
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