Physics · Class 11 Science
Ch 8Mechanical Properties of Solids — Class 11 Physics, concept-first.
Push a spring and let it go: it springs back. Squeeze a lump of putty and let it go: it stays squeezed. Both are solids, both were deformed by a force, and yet they respond in completely opposite ways once the force is removed -- this contrast is the starting point of the whole chapter.
Key concepts
Hover a concept to preview it and jump to its most relevant Q&A.
Young's Modulus
Young's modulus , named after the physicist Thomas Young, is the modulus of elasticity associated with a change in length of an object such as a wire, rod or beam — the elasticity of length. It applies to solids only.
Most relevant Q&A
- A steel rod of length $1.5\ \text{m}$ and cross-sectional area $2.5\times10^{-4}\ \text{m}^2$ is stretched by a tensile force of $75{,}000\…Free
- The steel cable of a crane or a suspension bridge is deliberately made both thick (large cross-sectional area) and relatively short rather t…Preview
- A metal wire of length $2.0\ \text{m}$ and diameter $0.8\ \text{mm}$ has a mass of $4.0\ \text{kg}$ hung from its lower end, producing an ex…Free
In previous exams
How often this chapter’s concepts have been examined — real appearance data, never estimated.
Chapter contents
The NCERT structure, section by section. Open a section to see its questions, then read the concept-first solution.
Introduction: Elastic and Plastic Behaviour of Materials
Push a spring and let it go: it springs back. Squeeze a lump of putty and let it go: it stays squeezed.
Stress and Strain
When a deforming force is applied to a solid body, the body develops an internal restoring force in response, exactly equal in magnitude and opposite in direction to the applied force once the body se…
Hooke's Law
Robert Hooke, in 1676, first stated the empirical law that governs elastic deformation for small enough stresses: within a certain limiting value of stress, called the proportional limit, the strain p…
The Stress-Strain Curve
Hooke's law describes only the initial, small-stress part of a material's elastic response. To see the complete picture -- how a material behaves as the stress on it is increased steadily, all the way…
Young's Modulus (Y)
Young's modulus, denoted , is the modulus of elasticity that applies to tensile (or compressive) stress and the corresponding longitudinal strain -- it is, in other words, the slope of the straight-li…
Shear Modulus of Rigidity (η)
The shear modulus of rigidity, denoted (also written or in some textbooks), is the modulus of elasticity that applies to shearing stress and the corresponding shearing strain -- the elastic constant g…
Bulk Modulus (K)
The bulk modulus, denoted , is the modulus of elasticity that applies to hydraulic (volume) stress and the corresponding volume strain -- the elastic constant governing how strongly a body resists a u…
Poisson's Ratio (σ)
When a rod or wire is stretched by a tensile force along its length, careful measurement shows that it does not merely become longer -- it also becomes very slightly thinner, contracting a small amoun…
Relation between Y, K, η and σ
Sections 8.5-8.8 introduced four elastic quantities for a solid material -- Young's modulus , the bulk modulus , the shear modulus of rigidity , and Poisson's ratio -- treating each, so far, as though…
Elastic Potential Energy in a Stretched Wire and a Spring
Stretching a wire, or extending a spring, requires doing work against the body's internal restoring force.
Summary
This chapter developed the mechanics of elastic solids from first principles, along exactly the topics WBCHSE's Unit 7 SUB TOPIC 1 lists:
More questions
17 Q+−Show 5 questionsHide questions5 questions
- Example 1A steel rod of length $1.5\ \text{m}$ and cross-sectional area $2.5\times10^{-4}\ \text{m}^2$ is stretched by a tensile force of $75{,}000\…Free
- Example 2A metal cube of side $10\ \text{cm}$ has its lower face fixed to a rigid table. A tangential force of $4000\ \text{N}$ is applied uniformly…Free
- Example 3A solid sphere of volume $1000\ \text{cm}^3$ is lowered into a fluid where it experiences a uniform increase in pressure of $2.0\times10^{7}…Preview
- Example 4Using the steel rod of Example 1 (length $1.5\ \text{m}$, area $2.5\times10^{-4}\ \text{m}^2$, stretched by $75{,}000\ \text{N}$, elongation…Preview
- Example 5A steel wire of original diameter $2.0\ \text{mm}$ is stretched so that it develops a longitudinal strain of $1.5\times10^{-3}$. If careful…Preview
+−Show 6 questionsHide questions6 questions
- Q6Distinguish between elastic behaviour and plastic behaviour of a material, giving one everyday example of a nearly perfectly elastic body an…Free
- Q7Three kinds of stress can act on a body: tensile (or compressive) stress, shearing stress, and hydraulic (volume) stress. Explain, with one…Free
- Q8State Hooke's law of elasticity in words and as an equation. Explain, in terms of a stress-strain graph, exactly what the "proportional limi…Preview
- Q9Sketch (in words) the shape of the stress-strain curve for a ductile metal such as mild steel as it is loaded from zero stress until it fina…Preview
- Q10The steel cable of a crane or a suspension bridge is deliberately made both thick (large cross-sectional area) and relatively short rather t…Preview
- Q11State the relation connecting Young's modulus ($Y$), bulk modulus ($K$), the shear modulus of rigidity ($\eta$), and Poisson's ratio ($\sigm…Preview
+−Show 6 questionsHide questions6 questions
- Q12A metal wire of length $2.0\ \text{m}$ and diameter $0.8\ \text{mm}$ has a mass of $4.0\ \text{kg}$ hung from its lower end, producing an ex…Free
- Q13A solid copper sphere of volume $500\ \text{cm}^3$ is lowered into the sea to a depth where the pressure on it increases by $1.1\times10^{7}…Free
- Q14A metal block used as a shear-test specimen has height $25\ \text{cm}$. A tangential force of $3.0\times10^{4}\ \text{N}$ is applied uniform…Preview
- Q15A wire of cross-sectional area $4\times10^{-6}\ \text{m}^2$ and length $3.0\ \text{m}$ is stretched by a force of $200\ \text{N}$, producing…Preview
- Q16A spring of force constant $250\ \text{N/m}$ is stretched by $8.0\ \text{cm}$ from its natural length. Calculate (a) the restoring force in…Preview
- Q17For a certain isotropic elastic solid, the bulk modulus is $K = 1.6\times10^{11}\ \text{Pa}$ and the shear modulus of rigidity is $\eta = 6.…Preview