Ch 6Mechanical Properties of Solids — Class 11 Physics, concept-first.

Every solid is built from atoms (or groups of atoms) locked into a definite geometric arrangement. Nature chooses this particular arrangement because, in it, the net force on each atom from all its ne…

A body is called an elastic body, and the underlying property is called elasticity, if it regains its original shape and size completely once the deforming force acting on it is removed.

The elastic response of a body is described quantitatively using two paired concepts: stress and strain.

In 1676, the English physicist Robert Hooke, studying how much a wire stretches under tension, discovered a simple relationship between stress and strain that now bears his name.

Since a deforming force can change a body's length, its volume, or its shape — and each of these three kinds of change has its own associated stress and its own associated strain (section 6.3) — it fo…

Young's modulus, named after the British physicist Thomas Young (1773-1829), is the modulus of elasticity associated with a change in length of an object such as a metal wire, rod, or beam under an ap…

Bulk modulus is the modulus of elasticity associated with a change in the volume of an object under an applied deforming force — hence it is also called the elasticity of volume.

The modulus of elasticity associated with a change in the shape of an object — with no accompanying change in its size — is called the modulus of rigidity, or shear modulus, usually denoted .

When a wire, fixed at one end, is stretched by a force applied at its free end, two things happen simultaneously: the wire's length increases, and its diameter decreases slightly — the wire becomes bo…

To map out how a material behaves under increasing stress, all the way up to the point where it finally breaks, a metal wire is suspended vertically from a rigid support and progressively loaded at it…

When a wire is stretched by a gradually increasing force, work is done on it, and this work is stored in the wire as elastic potential energy, called strain energy — the same energy that is released a…

Hardness is the property of a material that describes its ability to resist plastic (permanent) deformation when a load is applied to it — the harder a material is, the greater the resistance it offer…

Whenever the surface of one body slides — or tends to slide — over the surface of another, each body exerts a tangential opposing force on the other, directed opposite to the relative motion (or impen…

It might seem natural to assume that friction arises simply because two touching surfaces, however smooth they look, are actually covered in microscopic bumps and grooves that mechanically interlock —…

Depending on whether, and how, one surface is actually moving relative to another, friction is classified into three distinct types.