30 Questions
What is the force that causes a wire to break called?
Breaking force
What is the temporary loss of elastic properties due to repeated alternating deforming forces called?
Elastic fatigue
Why does a wire of double the thickness of another wire bear a maximum force four times that of the thinner wire?
Because the area of cross-section of the thicker wire is four times that of the thinner wire
Why do spring balances show wrong readings after they have been used for a long time?
Due to elastic fatigue
What is the significance of the point B on the stress-strain curve?
It is the point at which the wire begins to flow and break
What is the time delay in regaining original shape after removal of deforming force called?
Elastic after effect
What is the property of matter that enables it to regain its original shape and size after removal of deforming force?
Elasticity
What is the ratio of normal stress to volumetric strain within the elastic limits called?
Bulk modulus
What occurs when a force is applied to a body, resulting in internal restoring forces?
Stress
Why is the working stress of a wire always kept lower than the breaking stress?
To prevent the wire from breaking
What is the nature of stress in a beam when it is bent?
May be compressive or tensile
What happens to a material when it is subjected to a stress that exceeds its elastic limit?
It undergoes a permanent change in shape
What is the elasticity of a rigid body?
Infinite
What is the bulk modulus of elasticity of a gas?
Low
What is the torque required to produce a unit twist in a hollow shaft?
$\frac{\pi\eta (r_2^4 - r_1^4)}{2l}$
What is the work done in twisting a cylinder through an angle θ?
It is equal to $\frac{1}{2}Cθ^2$.
What is the range of Poisson's ratio in theoretical value?
-1 < σ < 0.5
What is the relation between Y, k, η and σ?
All of the above
What happens to the radius of a bar when it is stretched?
It decreases
What is the expression for volumetric strain?
dV / V
What is the angle of twist in torsion of a cylinder?
θ = τL / GJ
What is the elastic constant related to the change in volume of a material?
Bulk modulus
What is the torsional rigidity of a cylindrical shell proportional to?
Radius to the fourth power
What is the work done in twisting a cylinder through an angle θ proportional to?
θ squared
What is the unit of volumetric strain?
Unitless
What is the torque required to produce a unit twist in a solid shaft?
$\frac{\pi r^4}{l}$
What is the range of Poisson's ratio in theoretical value?
-1 < σ < 0.5
If a long bar has a length L and radius r, what is the expression for the volumetric strain?
dV / V = (dl / L) + (2dr / r)
What is the modulus of elasticity related to the change in shape of a material?
Young's modulus (Y)
What is the relationship between Y, k, η, and σ?
Y = 9Kη / (3K + η), σ = (3K - 2η) / (6K + 2η)
Learn about the concept of breaking stress and breaking force in relation to the mechanical properties of solids. Understand how breaking force depends on the area of cross-section of the wire and how breaking stress is a constant for a given material.
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