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Have you ever tested how a metallic spring appears to be elongated when you pull it and it closed back immediately after letting it off? This common observation is a perfect demonstration of the teaching of Class 11 Physics Chapter on 8 on Mechanical Properties of Solids. This chapter explores ways that different materials respond to forces such as tension, compression, and shear and engineers rely on this information in designing bridges, buildings and parts of machines to resist stress. The chapter is an important for CBSE Class 11 Physics syllabus as it underlies concepts of material strength and deformation that not only play a vital role in the examination preparation but also constitutes a prominent part of competitive examinations such as JEE, NEET and other engineering or medical-related entrance exams.
Class 11 Physics Notes of Mechanical Properties of Solids, provided by subject experts, present complex ideas in simplified ways that help students to understand them easily. The notes emphasize clarity of concepts and are perfect to refresh during rapid revision, numerical problems, or revising important topics before exams. These notes includes important formulas and derivations to use when solving problems, diagrams to improve clarity, practice questions and concept highlights. You need to study this chapter well whether you are taking up CBSE board examination or aiming to score well in competitive entrance examinations. The notes are a solid support guide that will assist you in revision and ensure a confident face towards theory and numericals.
Also, students can refer,
NCERT Class 11 Physics Chapter 8 Notes Mechanical Properties of Solids provide a brief but clear outline of how solids react to such forces as stretching, compression, hinging, and bending. These notes helps students help in grasping some of the most important concepts such as stress, strain, Hooke's law and are ideal in brush up or revision and examinations.
1. Elasticity: Elasticity is a quality that allows an object to restore its original shape after an external force is removed. This implies it shows us how flexible a person's body is. Take, for example, a spring. When a spring is stretched, its shape changes, and when the external force is removed, the spring returns to its original position.
2. Plasticity is the opposite of elasticity. The term "property" refers to a state of permanent deformation. Even when the external force is eliminated, the object never returns to its previous shape. Plastic is the name for these types of items.
3. Ductility: It refers to the ability to be pulled into thin wires or sheets. for example:-Small gold
4. Strength: The ability to resist a high level of applied stress without failing.
Stress = F/A (mathematically)
Where F is the restoring force that emerges in the body as a result of the force we apply.
A=area
It produces a change in volume and density, shape remaining the same.
It occurs in solids, liquids or gases
In the case of fluids, only bulk stress can be found.
It is equal to a change in pressure because the change in pressure is responsible for change in volume.
Volume stress
Strain = ΔL/L, where ΔL is the length change.
L stands for the original length.
Consider a cube with an initial length of L that is in a certain position and is shifted by an angle θ. Let x represent the modest relative displacement.
stress ∝ strain
stress = k × strain
The proportionality constant, k, is also known as the modulus of elasticity.
Young's modulus is greater than the shear modulus.
G = Y/3 is there for most material
Here represents p =hydraulic stress, ΔV/V = hydraulic strain
The letter 'K' stands for this.
k=1/B = - (1/p) (ΔV/V)
k(solids)<k(liquids)<k(gases)
We can also write,
Also, Potential energy per unit volume
Q1: A mild steel wire of length 2L and cross-sectional area A is stretched, well within elastic limit, horizontally between two pillars Figure mass m is suspended from the mid point of the wire. Strain in the wire is:
Answer:
Q2: A rigid bar of mass M is supported symmetrically by three wires each of length L. Those at each end are of copper and the middle one is of iron. The ratio of their diameters, if each is to have the same tension, is equal to:
Answer:
As the bar is supported symmetrically by the three wires, therefore extension in each wire is the same.
Let T be the tension in each wire and the diameter of the wire is D , then Young's modulus is
As F and
Hence,
or
Now, we can find ratio as
Q3: Consider two cylindrical rods of identical dimensions, one of rubber and the other of steel. Both the rods are fixed rigidly at one end of the roof. A mass M is attached to each of the free ends at the centre of the rods. Then:
(a) Both the rods will elongate but there shall be no perceptible change in shape
(b) The steel rod will elongate and change shape but the rubber rod will only elongate
(c) The steel rod will elongate without any perceptible change in shape, but the rubber rod will elongate and the shape of the bottom edge will change to an ellipse
(d) The steel rod will elongate, without any perceptible change in shape, but the rubber rod will elongate with the shape of the bottom edge tapered to a tip at the centre
Answer:
Thus, when mass
Hence, the correct option is (d)
NCERT Class 11 Notes Chapter-Wise
The elastic modulus is defined as the ratio of tension to strain.
The elastic modulus is a property of each material.
This means that gold will have a specific elastic modulus value, and rubber will have a specific elastic modulus value, and so on.
Volume Strain
The ratio of change in volume to the original volume as a result of hydraulic stress is known as volume strain.
Strain
Strain is a deformation measurement that represents the displacement of particles in the body in relation to a reference length.
Hooke's law
Within the elastic limit, Hooke's law asserts that the stress developed is directly proportional to the strain produced in a body.
No, the NCERT notes for Class 11 Physics chapter 9 do not include all of the important derivations. This NCERT note summarizes the chapter's important points and equations and can be used to review the Mechanical Properties of Solids.
From the notes for Class 11 Physics chapter 9, students should expect 4 to 6 mark questions, and they can use this note for quick revision to help them improve their grades.
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