Find the height ȳ of the centroid of the T-section above its bottom edge.
Centroid & second moment of area worksheet with answers
A solid circular bar has diameter D = 100 mm. Find its second moment of area Ix about a diameter.
A 100 mm × 240 mm plate has a circular hole of diameter 50 mm on its vertical centre line, with its centre 144 mm above the bottom. Find the second moment of area Ix about the horizontal axis through the centroid.
A 100 mm × 200 mm plate has a circular hole of diameter 40 mm on its vertical centre line, with its centre 60 mm above the bottom. Find the second moment of area Ix about the horizontal axis through the centroid.
A welded I-section has a top flange 150 × 10 mm, a web 170 mm high and 8 mm thick, and a bottom flange 210 × 14 mm (width × thickness). Find its second moment of area Ix 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 50 kN·m. Find the bending stress σbottom at the bottom edge.
Answer key
- 1. ȳ = 229.7 mm
- 2. Ix = 4.909 × 10⁶ mm⁴
- 3. Ix = 113.7 × 10⁶ mm⁴
- 4. Ix = 64.4 × 10⁶ mm⁴
- 5. Ix = 37.21 × 10⁶ mm⁴
- 6. σbottom = 139.2 MPa
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