Mechanical Engineering - Strength of Materials - Discussion

In this question strictly say "Cooled".

So, past tense use.
Hence when cooling Compressive stress developed.
After Cooled tensile stress developed.

Ans:- no stress.

If the bar is cooled to 5 degrees C, Contraction takes place. Or If the bar is heated, expansion takes place, based on temperature differences.

But no stress here developed. Because it's free expansion. There is no opposing force/resisting area is there.

Remembering stress formula.

"Total resistance per unit area of cross-section". In the given question "area is varying like a contraction but no resistance".

In order to prevent the free expansion. The bar must be fixed on both ends or pulling or pushing load must act on it. The only possibility of stress was developed either it may compressive or tensile based on type load acting on it.

So, please change the answer to ***no stress***.

Yes you are right @ Taniya.

Temperature has no relation with stress so it will be no stress.

Tensile stress will be induced when bar get cooled its starts shrinking. As a result, It like a compressive load acting on it, for resisting this internal resistance is developed which is tensile stress.

It depends on the configuration of a bar. If the bar is free at both ends and no restriction whatsoever, then no stresses will be developed.

If it is constrained, when we cool the bar it tends to shrink which develops tensile stress inside the bar.

Similarly, when we heat the bar it tends to expand and due to constraint compressive stresses are developed.

When cooling contraction takes place, but the bar develops Tensile stress, it will try to oppose the contraction.

I think the answer should be no stresses, as the bar is contracting freely.

Suppose the bar is fixed at both the ends and it is being cooled, then in order to maintain it's true state tensile stresses will be induced in bar.

In similar manner if a fixed bar is being heated it won't expand and compressive stresses will be induced in bar.

If we assume the body is fixed due to cooling body try to contrast which leads to the development of tensile stress to overcome that induced compressive stress.

@Aditi, I do agree with your explanation.