Two beams have the same cross-sectional area and are made of the same material. Beam 1 has a solid rectangular cross-section. Beam 2 has an I-shaped cross-section, formed by redistributing the same amount of material so that more area is located far from the horizontal centroidal axis in the top and bottom flanges, with a thin web connecting them. Both beams are subjected to the same bending moment about their horizontal centroidal axis. Which statement best explains why Beam 2 resists bending more effectively than Beam 1?

Question

Answer

Beam 2 has a larger second moment of area (I). By placing more material far from the neutral axis, the flanges make a large contribution to (I=\int y^2 dA), so the same bending moment produces lower curvature and lower bending stress.

100%

Answer

Beam 2 has a higher centroid, so the neutral axis is further from the applied load.

Answer

The web of Beam 2 removes material near the neutral axis, where bending stress is highest, directly reducing the maximum bending stress.

Answer

Beam 2 has more total area, so there is more material to resist the bending load.

Answer

Beam 2 distributes bending stress uniformly across the cross-section, so the peak stress is reduced.

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Two beams have the same cross-sectional area and are made of the same material. ...

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