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
Discussion:
105 comments Page 2 of 11.
Phaneendra said:
3 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.
But here the bar is not under any restraints. So there will be no stress.
(11)
Navaj M said:
8 years ago
Actually, first clear that, stress means an internal pressure which resists the external deformation.
After that whenever anybody is cooled it undergoes shrinkage that means externally compressive force is subjected therefore to resist them internally pressure developed is nothing but tensile stress.
After that whenever anybody is cooled it undergoes shrinkage that means externally compressive force is subjected therefore to resist them internally pressure developed is nothing but tensile stress.
Ravi said:
1 decade ago
Compressive stress is the answer (strain is a reacting force to stress, hence the strain is tensile). As far as option a is considered, stress relieving starts at 450 degrees C. Simply because metals expand on heating and contract on cooling direct effect of which will be considered stress!
Syam said:
8 years ago
Tensile stress will be induced if and only if both the two ends are fixed. If ends are not fixed no stress will be induced. So Whenever a body is heated it expands and when allowed to cool it normally contracts. Its the natural behavior of material so compression stress is the right answer.
S.VISHAL said:
9 years ago
Stress is the resistance offered by a material to resist the deformation caused by the force acting. Over here since it is cooling, compressive stress will be acting on the body and the body opposes by tensile force hence TENSILE force is induce in the body. Hence the answer is correct.
Hamed said:
9 years ago
The bar is fixed in both ends, when cooling bar to -5 the bar will shranking because change in temperatue this will produce a reaction forces in both ends will trying to opposite the action of shrinking so those forces will produce tensile stress in the body. Thank you.
Agoda isaac said:
1 decade ago
A bar is compressive when cooling because when cooling it is contrasting and as we know compression forces are forces that act inwardly in a body while expansion is tensile force because it is elongating the bar that is, the forces acting away from the bar.
RAHUL S said:
8 years ago
As the metal froze to -5 ° It will start to shrink. As it start to shrink the length of the metal start to increase if and only if it is free from external forces (restricted forces). Due to increase in length it is said be acted upon by tensile force.
Akshay said:
1 decade ago
Stress = internal resistance therefore when the bar is cooled it just shrinks, there is no internal resistance offered by the body until and unless the bar is constrained to shrink by holding it at both ends. Hence answer should be no stress.
Lokesh singh said:
10 years ago
During the time of cooling the bar will go under shrinkage. But when the bar will be taken away from cooling area then it will try to get its original size then tensile force will occurs inside it. So tensile stress should be the answer.
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