A 120 mm × 200 mm plate has a circular hole of diameter 40 mm on its vertical centre line, with its centre 140 mm above the bottom edge. 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.
Find the second moment of area Ix of the T-section about the horizontal axis x through its centroid.
A 120 mm × 150 mm plate has a circular hole of diameter 30 mm on its vertical centre line, with its centre 97.5 mm above the bottom. Find the second moment of area Ix about the horizontal axis through the centroid.
A symmetric I-section has flanges 180 mm wide and 14 mm thick, an overall depth of 280 mm and a web 6 mm thick. It carries a bending moment of 150 kN·m about the axis x. Find the size of the bending stress σj at the junction of the web and the top flange.
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.
Answer key
- 1. ȳ = 97.79 mm
- 2. ȳ = 137.2 mm
- 3. Ix = 60.72 × 10⁶ mm⁴
- 4. Ix = 33.34 × 10⁶ mm⁴
- 5. σj = 194.4 MPa
- 6. σbottom = 160.5 MPa
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