Mechanical Engineering - Strength of Materials - Discussion

Discussion Forum : Strength of Materials - Section 1 (Q.No. 34)
34.
When a bar is cooled to - 5°C, it will develop
no stress
shear stress
tensile stress
compressive stress
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
105 comments Page 1 of 11.

Phaneendra said:   2 years ago
If the bar is cooled, it will shrink. But the internal forces will resist that by producing force in opposite direction to shrinkage which means the internal forces produce tension. So the answer is tensile stress if the bar is fixed.

But here the bar is not under any restraints. So there will be no stress.
(8)

Ajant pandey said:   2 years ago
If the temperature of the bar is lowered, then the nature of stress & strain will be?

Ishfaq paray said:   3 years ago
Correct answer is tensile stress.

Here -5 degrees denotes that there will be an initial temperature
Thermal stress= E alpha ΔT,
ΔT= T2-T1.

If T2 is -10 degrees that means ΔT =-10-(-5)=-5 degree which means compressive,
If T2 =10 degree.

ΔT= 10-(-5)=15 which means tensile stress . So the answer will be tensile.
(2)

Atanu said:   3 years ago
When a bar is cooled to - 5° C, it will develop.

Actually, this question denoted 'a bar '.

It is not Mentioned as the bar is fixed, hinged, both sides fixed it. So the bar is free, not fixed and hinged.

That's why the answer is ' no stress '.

(If it is mentioned as "one side is fixed" then the answer is compressive stress generate).

Thank you.
(2)

Rajesh kumar patel said:   3 years ago
The right answer is compressive stress.

And when free bar then hired then no thermal stress dovlepod.
(1)

Sujit Mundhe said:   4 years ago
We know that Stress means Internal Stress/Area

If bar at -5' obviously it goes to compression & hence to resist this compression tensile stress is develop in rod to get its actual length.
(2)

Santy. said:   4 years ago
When the bar is cooled. It has been prevented for expansion. So it is try to expands. So there will tensile stress is produced.

SOURABH said:   5 years ago
No stress will be developed.

Harsh said:   5 years ago
If end conditions are not given then what should we assume (fixed or free) ? Please explain me.

Raaja said:   5 years ago
Tensile, when both the ends are fixed in cooling. Compressive, when both the ends are under restriction during heating. If no restrictions there is no stress will develop.


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