Test: Mechanical Properties of Solids (October 8) - NEET MCQ

Stress = F⟂/A = (Mass x Acceleration⟂)/Cross-sectional Area

= (550 kg x 9.8 m/s²)/ (0.30×10−4 m²)

= 1.8×10⁸ Pa

Young's ModulusSteel (Y) = 20×10¹⁰ Pa = Stress/Strain

=> Strain = Stress/Y = 1.8×108 Pa / 20×10¹⁰ Pa

= 9.0×10⁻⁴ 

Y=F x l/A x Δ l
Δ l=0.5cm=0.5x10^-2m, l=10M, F=940N
Y=20x10¹⁰pa
20x10¹⁰=940x10/πr²x0.5x10^-10
πr²=94x100/5x10^-3x2x10¹¹=94x10²/10x10⁸
r²=94/π x 10^-7 =2.99 x 10^-6
r2 ≅3x10^-6
r=1.13x10^-10 m
diameter=2r=3.6mm

An elastomer is a polymer with viscoelasticity (i. e., both viscosity and elasticity) and very weak intermolecular forces, and generally low Young's modulus and high failure strain compared with other materials. Elastomer rubber compounds are made from five to ten ingredients, each ingredient playing a specific role. Polymer is the main component, and determines heat and chemical resistance, as well as low- temperature performance. Reinforcing filler is used, typically carbon black, for strength properties.

Shear modulus or modulus of rigidity is the ratio of shearing stress to the corresponding shearing strain, by the definition of shear modulus.

I section is generally used as a beam because of its high section modulus as its most of the area is situated away from its neutral axis hence it has high moment of inertia i.e. high section modulus i.e. high moment carrying capacity which is the major requirement for a good beam section.

F/A = e/L
F/A = 0.18/l ( let the length be l)
F/A = x/2l
0.18/L = x/2l
0.18×2l = xl
0.36l = xl
x = 0.36

Stress has its own SI unit called the Pascal. 1 Pascal (Pa) is equal to 1 N/m². In imperial units stress is measured in pound force per square inch which is often shortened to "psi". The dimension of stress is same as that of pressure.