Physics

Introduction to Sound Waves

1. Sound waves are mechanical waves that require a medium for propagation.
2. They are longitudinal waves, where particles in the medium oscillate parallel to the direction of wave travel.
3. Vibrations in a source generate sound waves, which travel through air, liquids, and solids.
4. Sound cannot propagate through a vacuum as it requires a medium with particles.

Production of Sound

1. Sound is produced when an object undergoes

Introduction to Wave Properties

1. Waves are disturbances that transfer energy from one point to another without the transport of matter.
2. The primary properties of waves include wavelength, frequency, amplitude, and speed.
3. These properties describe the behavior and nature of waves in different media.

Wavelength (λ)

1. Wavelength is the distance between two consecutive points in phase on a wave, such as two cre

Introduction to Waves

1. A wave is a disturbance or vibration that travels through a medium or space, transferring energy.
2. Waves are classified into two main types: transverse and longitudinal, based on the direction of particle motion relative to wave propagation.
3. Waves can travel through various media like solids, liquids, and gases.

Transverse Waves

1. In transverse waves, particles of the medium move perpendicularly to the direction of wav

General Overview

1. Thermal expansion is the tendency of materials to expand or contract with changes in temperature.
2. It is a crucial factor in the design of various structures and devices to prevent damage or failure.
3. The phenomenon is applied in engineering, construction, and daily life to ensure safety and functionality.

Applications in Railway Tracks

1. Railway tracks are made of steel, which expands during hot weather and contracts during

General Overview

1. Thermal expansion refers to the increase in the size (length, area, or volume) of a material due to an increase in temperature.
2. The extent of expansion depends on the material properties and the degree of temperature change.
3. The coefficient of expansion is a measure of how much a material expands per degree change in temperature.

Coefficient of Linear Expansion

1. The coefficient of linear expansion (α) describes the change

General Concepts of Thermal Expansion

1. Thermal expansion is the increase in the size (length, area, or volume) of a substance when its temperature is increased.
2. It occurs due to an increase in the kinetic energy of particles, which increases the separation between them.
3. Thermal expansion is observed in solids, liquids, and gases.
4. The degree of expansion depends on the material properties and the amount of temperature change

Heat Engines

1. A heat engine is a device that converts heat energy into mechanical work.
2. It operates between a hot reservoir and a cold reservoir.
3. The working principle is based on the First and Second Laws of Thermodynamics.
4. The efficiency of a heat engine is given by η = W/Q₁, where:
   • W is the work output.
   • Q₁ is the heat absorbed from the hot reservoir.

Entropy

1. Entropy is a measure of the disorder or randomness of a system.
2. The symbol for entropy is S, and its SI unit is joules per kelvin (J/K).
3. It quantifies the unavailability of a system's energy to perform useful work.
4. The Second Law of Thermodynamics states that entropy always increases in a spontaneous process.
5. ΔS = Q/T, where:
   • ΔS is the change in entropy.
   • Q is the heat exchanged.

Zeroth Law of Thermodynamics

1. The Zeroth Law of Thermodynamics defines the concept of thermal equilibrium.
2. If two systems are each in thermal equilibrium with a third system, they are in thermal equilibrium with each other.
3. This law provides the foundation for the definition of temperature.
4. Thermometers work based on the Zeroth Law.

First Law of Thermodynamics

1. The First Law of Thermodynamics is a statement of the conservat

1. Thermal conductivity is a material's ability to conduct heat.
2. It is denoted by the symbol k or λ.
3. The SI unit of thermal conductivity is watt per meter per kelvin (W/m·K).
4. Fourier's Law describes heat conduction: Q = -kA(dT/dx), where:
   • Q is the heat transfer rate.
   • k is the thermal conductivity.
   • A is the cross-sectional area.
   • dT/dx is the temperature gradient.