A 120 mm × 240 mm plate has a circular hole of diameter 60 mm on its vertical centre line, with its centre 84 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.
A 200 mm × 150 mm plate has a circular hole of diameter 40 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.
The T-section is used as a beam with the flange on top and carries a sagging bending moment of 5 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 90 MPa in compression. Find the largest hogging bending moment Mallow the beam can carry (give its size).
Answer key
- 1. ȳ = 123.9 mm
- 2. ȳ = 164.2 mm
- 3. Ix = 55.83 × 10⁶ mm⁴
- 4. Ix = 16.76 × 10⁶ mm⁴
- 5. σtop = 15.89 MPa
- 6. Mallow = 25.7 kN·m
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