Find the height ȳ of the centroid of the T-section above its bottom edge.
Centroid & second moment of area worksheet with answers
A 200 mm × 240 mm plate has a circular hole of diameter 40 mm whose centre is 50 mm from the left edge (at mid-height). Find the distance x̄ of the centroid from the left edge.
A 100 mm × 150 mm plate has a circular hole of diameter 30 mm on its vertical centre line, with its centre 90 mm above the bottom. Find the second moment of area Ix about the horizontal axis through the centroid.
Find the second moment of area Ix of the T-section about the horizontal axis x through its centroid.
A 100 mm × 300 mm plate has a rectangular cut-out 50 mm wide and 30 mm high, centred on the vertical centre line with its centre 180 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 20 kN·m. Find the size of the bending stress σtop at the top edge.
Answer key
- 1. ȳ = 181.1 mm
- 2. x̄ = 101.3 mm
- 3. Ix = 27.92 × 10⁶ mm⁴
- 4. Ix = 45.17 × 10⁶ mm⁴
- 5. Ix = 223.5 × 10⁶ mm⁴
- 6. σtop = 123.5 MPa
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