An L-shaped angle section has a horizontal leg 120 mm wide and a vertical leg 250 mm high (both measured overall). Both legs are 22 mm thick. Find the height ȳ of the centroid above the bottom edge.
Centroid & second moment of area worksheet with answers
Find the height ȳ of the centroid of the T-section above its bottom edge.
A channel section lies with its open side up: a base plate 300 mm wide with two upright legs, 190 mm high overall. Base and legs are all 8 mm thick. Find its second moment of area Ix about the horizontal axis x through its centroid.
A 200 mm × 300 mm plate has a circular hole of diameter 30 mm on its vertical centre line, with its centre 195 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 40 kN·m. Find the size of the bending stress σtop at the top edge.
A cast-iron beam has the T-section shown, with the flange on top. The allowable stresses are 50 MPa in tension and 100 MPa in compression. Find the largest sagging bending moment Mallow the beam can carry.
Answer key
- 1. ȳ = 92.9 mm
- 2. ȳ = 189.8 mm
- 3. Ix = 19.92 × 10⁶ mm⁴
- 4. Ix = 448.5 × 10⁶ mm⁴
- 5. σtop = 77.6 MPa
- 6. Mallow = 17.35 kN·m
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