Question

A 1.25 cm diameter bar is subjected to a load of 2500 kg. Calculate the engineering stress on the bar in megapascals (MPa):

• A. 600 MPa
• B. 400 MPa
• C. 200 MPa
• D. 100 MPa

Hint:

For stress calculations in SI units, always convert load (kg) to force (N) by multiplying with 9.81m/s^2

Answer 1

The Correct Option is C

Engineering stress is given by:
\[\sigma = \frac{F}{A}\]
Here, $F = 2500 \text{ kg} \cdot 9.81 \text{ m/s}^2 = 24,525 \text{ N}$, $A = \pi \left( \frac{d}{2} \right)^2 = \pi \left( \frac{1.25 \times 10^{-2}}{2} \right)^2 \text{ m}^2$:
\[A \approx 1.227 \times 10^{-4} \text{ m}^2, \quad \sigma = \frac{24,525}{1.227 \times 10^{-4}} \approx 200 \text{ MPa}\]