Comparing elastic (bending) strength for rectangular beams of different widths Beam A and Beam B have the same length and depth d; Beam B has double the width b of Beam A. Determine how the elastic bending strength of Beam B compares to Beam A. Choose the correct option.
Mechanical Engineering
Strength of Materials
Difficulty: Easy
Choose an option
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Asame
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Bdouble
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Cfour times
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Dsix times
Answer
Correct Answer: double
Explanation
GivenRectangular section: width = b, depth = d. Beam B has width 2b, same d.
Concept/ApproachElastic bending strength ∝ section modulus Z.For a rectangle: Z = bd²/6.
Step-by-stepZA = b d²/6ZB = (2b) d²/6 = 2 × (b d²/6) = 2 ZA
ConclusionStrength (at same allowable stress) doubles.
Final Answerdouble