Timber MCQ with answer and solution

Concept

Timber is strongest in tension along the grain, because the long fibres carry the load directly.

Step-by-step solution

1. Timber strength depends on the direction of the load compared to the grain. 2. Along the grain (parallel to fibres), tension is carried by long, strong fibres, so strength is high. 3. Standard textbook value for tensile strength parallel to fibres is about 80 – 190 N/mm². 4. So option B is correct.

Explanation

Timber fibres are long and strong. When pulled along their length, they give high tensile strength of about 80 – 190 N/mm². Across the grain, tensile strength is very low.

Why the other options are wrong

A: 10 – 80 N/mm² is too low and is closer to compressive or cross-grain values. C: 190 – 250 N/mm² is too high for normal timber. D: 250 – 310 N/mm² is close to mild steel strength, not timber.

Shortcut

Timber tension along grain ≈ 80 – 190 N/mm². This is much more than across the grain.

Common mistake

Mixing up the tensile strength along the grain with the much lower values across the grain or in compression.