PHY01 CO6 YES

Thermodynamics

is the study of thermal energy

(internal energy) and temperature, focusing on

how heat transfers within systems.

Thermal Energy

Internal kinetic and

potential energy of particles.

Temperature

is an SI base quantity that reflects

how hot or cold an object is. Instruments such as

thermometers measure temperature through a

working substance that changes its physical

properties, such as pressure or length, in a

predictable way. Physicists measure temperature

using the Kelvin scale.

Triple point of water

Where liquid water, solid ice, and water vapor all

coexist in thermal equilibrium.

Zeroth law in thermodynamics

Two bodies are in thermal equilibrium when they

share the same temperature and no heat flows

between them. If body A is in thermal equilibrium

with body B, and body B is in thermal equilibrium

with body C, then body A is in thermal equilibrium

with body C.

Thermal Expansion

refers to the tendency of

materials to change in size when their

temperature changes. This behavior occurs

because atoms and molecules vibrate more

vigorously as temperature increases.

Linear expansion

describes how the length of a

material changes when temperature changes.

Area expansion

describes how a material's

surface area increases when heated.

Volume expansion

describes how a material

changes its size in three dimensions.

Liquid

expand when heated because the

increased movement of molecules pushes them

apart. The lack of a fixed shape does not prevent

expansion.

Heat

is the energy transferred between a system

and its environment due to a temperature

difference.

Positive

The system absorbs heat

from the environment.

Negative

The system absorbs heat

from the environment.

Thermal energy

is the total internal energy of a

substance.

● It includes the kinetic energy of moving

particles.

● It includes the potential energy from the

arrangement and interactions of particles.

● Thermal energy increases when heat

enters the system.

Specific heat

is the amount of heat required to

raise the temperature of 1 kilogram of a substance

by 1°C.

Heats of transformation

A substance does not

always change temperature when it absorbs

heat. Instead, it may undergo a phase change.

Latent heat

Latent heat is the energy required for a complete

phase change per unit mass.

Heat of Vaporization

This applies when matter changes between liquid

and gas.

Heat of Fusion

This applies when matter changes between solid

and liquid.

FIRST LAW OF THERMODYNAMICS

meaning

internal energy increases when heat enters and

decreases when the system does work. Energy

cannot be created or destroyed; it only changes

form.

Isobaric:

● Pressure remains constant

● Work is area under horizontal line

Isothermal

● Temperature constant

● Internal energy does not change

Adiabatic:

● No heat exchange (Q = 0)

● Rapid processes like

compression/expansion

Isochoric:

● Volume constant

● W = 0 always

SECOND LAW OF THERMODYNAMICS

Heat naturally flows from hot to cold, and no

engine can convert all heat to work. All real

processes increase entropy. Real-life example: A

hot cup of coffee cools down because heat

spreads out to the surroundings.

ENTROPY

is a measure of disorder or energy

spreading. It always increases in irreversible

processes.

ΔL

is the change in length

α

is the coefficient of linear expansion

L

is the original length

ΔT

is the change in temperature