The GATE Grind

GATE 2020 PI – Question 39

General Engineering · Applied Mechanics · 2 marks · Multiple choice

A simply supported beam of length L carries uniform transverse load W N/m. Its rectangular section has width b and depth t. Find the maximum bending-stress magnitude.

Diagram for GATE 2020 PI question 39
  1. $3WL^2/(4bt^2)$
  2. $4WL^2/(3bt^2)$
  3. $2WL^2/(3bt^2)$
  4. $3WL^2/(2bt^2)$

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (A) $3WL^2/(4bt^2)$

Explanation

Maximum moment is WL²/8 at midspan. The rectangular-section modulus is I/c=(bt³/12)/(t/2)=bt²/6. Therefore σmax=M/Z=(WL²/8)(6/bt²)=3WL²/(4bt²), A.

More Applied Mechanics questions

All Applied Mechanics questions →