Find the height ȳ of the centroid of the T-section above its bottom edge.
Centroid & second moment of area worksheet with answers
A rectangular section has width b = 60 mm and height h = 175 mm. Find its second moment of area Ibase about the axis along its bottom edge.
Find the second moment of area Ix of the T-section about the horizontal axis x through its centroid.
A 200 mm × 150 mm plate has a circular hole of diameter 60 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 120 mm × 240 mm plate has a rectangular cut-out 80 mm wide and 40 mm high, centred on the vertical centre line with its centre 156 mm above the bottom. Find the second moment of area Ix about the horizontal axis through the 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 size of the bending stress σtop at the top edge.
Answer key
- 1. ȳ = 122.5 mm
- 2. Ibase = 107.2 × 10⁶ mm⁴
- 3. Ix = 53.11 × 10⁶ mm⁴
- 4. Ix = 54.91 × 10⁶ mm⁴
- 5. Ix = 133.1 × 10⁶ mm⁴
- 6. σtop = 182.8 MPa
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