A 240 mm × 300 mm plate has a circular hole of diameter 50 mm whose centre is 72 mm from the left edge (at mid-height). Find the distance x̄ of the centroid from the left 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 200 mm × 240 mm plate has a circular hole of diameter 40 mm on its 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.
A welded I-section has a top flange 170 × 22 mm, a web 280 mm high and 14 mm thick, and a bottom flange 300 × 10 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 20 kN·m. Find the bending stress σbottom at the bottom edge.
Answer key
- 1. x̄ = 121.3 mm
- 2. ȳ = 225.1 mm
- 3. Ix = 6.481 × 10⁶ mm⁴
- 4. Ix = 228.6 × 10⁶ mm⁴
- 5. Ix = 172.6 × 10⁶ mm⁴
- 6. σbottom = 39.53 MPa
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