MECHANICAL PROPERTIES OF SOLIDS
Frequently Asked Questions
Mechanical properties describe how solids respond to applied forces, such as stretching, compressing, bending, or twisting.
Elasticity is the property of a material by which it regains its original shape and size after removal of the deforming force.
Elastic limit is the maximum stress up to which a material returns completely to its original dimensions when the force is removed.
Stress is the internal restoring force per unit area developed inside a material when an external force is applied.
Strain is the fractional change in dimension (length, volume, or shape) produced due to stress.
Stress = Force / Area
Strain = Change in dimension / Original dimension
Hooke’s law states that stress is directly proportional to strain within the elastic limit of a material.
Young’s modulus is the ratio of longitudinal stress to longitudinal strain.
Y = (Longitudinal stress) / (Longitudinal strain)
It indicates that the material is stiff and undergoes very little deformation under stress.
Bulk modulus is the ratio of volume stress to volume strain.
K = -?P / (?V / V)
Because an increase in pressure causes a decrease in volume.
Shear modulus is the ratio of shear stress to shear strain.
G = Shear stress / Shear strain
Poisson’s ratio is the ratio of lateral strain to longitudinal strain.
It usually lies between 0 and 0.5 for most materials.
The material shows no lateral contraction when stretched.
It is the energy stored in a material due to elastic deformation within elastic limit.
\(U =\frac{1}{2} (\frac{YA}{L}) l^2\)
It is a graph showing the relationship between stress and strain for a material.
It represents elastic behavior obeying Hooke’s law.
Yield point is the stress beyond which the material undergoes permanent deformation.
It is the point at which the material fractures and breaks.
Plasticity is the property of a material to undergo permanent deformation.
Steel is a good example of an elastic material within limits.
Clay exhibits plastic behavior.
Due to high Young’s modulus and strength, steel stretches very little under heavy loads.
They use elastic behavior to absorb shocks and vibrations smoothly.
High bulk modulus ensures efficient transmission of pressure in liquids.
It ensures safety, stability, and durability of structures under loads.
To prevent permanent deformation and mechanical failure.
Increase in temperature generally decreases elasticity of materials.
Steel is more elastic because it has a higher Young’s modulus.
Due to interatomic forces being slightly displaced under stress.
Tensile stress acts on a stretched wire.
Compressive stress acts on a pillar.
Shear stress acts during twisting.
It helps in selecting suitable materials and ensuring structural safety.
Elastic fatigue is the weakening of elastic properties due to repeated loading and unloading.
Due to elastic fatigue and repeated stress cycles.
No real material is perfectly elastic.
Pascal (Pa)
Yes, strain has no unit.
To allow thermal expansion and prevent buckling.
It helps strings vibrate at stable frequencies producing sound.
Due to its high elasticity and shock-absorbing ability.
It is elastic energy stored per unit volume of material.
It ensures safety, comfort, energy storage, and durability of objects we use daily.
