The Young's modulus of a steel wire of length \(6 m\) and cross-sectional area \(3 \,mm ^2\), is \(2 \times 10^{11}\) \(N / m ^2\). The wire is suspended from its support on a given planet A block of mass \(4 kg\) is attached to the free end of the wire. The acceleration due to gravity on the planet is \(\frac{1}{4}\) of its value on the earth The elongation of wire is (Take \(g\) on the earth \(=10\, m / s ^2\)) :
Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion (A) : 02 is liberated in the non-cyclic photophosphorylation.
Reason (R) : Liberation of oxygen is due to photolysis of water.
In the light of the above statements, choose the correct answer from the options given below
Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion (A) : The Cro-Magnon man was the direct ancestor of the living modern man.
Reason (R) : Cro-Magnon man had slightly prognathous face.
In the light of the above statements, choose the correct answer from the options given below
Stress and Strain are the terms in physics, which are used to explain deformation of solids.
Force applied per unit area is known as stress.
As a result of stress, change of shape is observed in the body. The change or deformity consequential to the stress acting on the body is called strain. Strain can be defined as the amount or measure of deformity that takes place due to the force applied on the object.
Strain is denoted with (ε). It has no units.
Longitudinal Strain = Δ L/L
The English scientist Robert Hooke, while studying spring and elasticity, noticed that many materials displayed an identical property when the stress-strain relationship was studied. There exists a linear region where the force required to stretch the material was proportional to the extension of the material; this is called Hooke’s law. Mathematically, the law is presented as:
F = -k.x
Where, F = the force
x = the extension length
k = spring constant in N/m