DEFINITION OF HEAT AND TEMPERATURE
HEAT: We all know that bodies can be heated (increasing
their internal energy) or cooled (losing internal energy).
The energy gained or lost in these processes is heat.
TEMPRATURE: Temperature is the average value of the
kinetic energy of these particles.
OUR PRESENTATION TROPIC IS TEMPERATURE AND LAWS OF
1. The heat lost or absorbed
by a body
1.The temperature can’t lost
or absorbed by a body
2. Specific heat is the
property of bodies
2. Specific temperature isn’t
the property of bodies
3.Heat don’t remains
3. Temperature remains
simply states that energy can be neither created nor
destroyed (conservation of energy). Thus power
generation processes and energy sources actually
involve conversion of energy from one form to another,
rather than creation of energy from nothing.
The 1st Law of Thermodyamics
SECOND LAW OF THERMODYNAMICS
The Second Law of Thermodynamics states that "in all energy
exchanges, if no energy enters or leaves the system, the
potential energy of the state will always be less than that of
the initial state."
This is also commonly referred to as entropy.
Energy changes are the driving force of the universe. The
driving force of all energy change is the unstoppable
tendency of energy to flow from high concentrations of
energy to lower concentrations of energy.
7ZEROTH LAW OF THERMODYNAMICS
The zeroth law of thermodynamics states that if two
systems, A and B, are in thermal equilibrium with a third
system, C, then A and B are in thermal equilibrium with
each other. It is analogous to the transitive property in
math (if A=C and B=C, then A=B). Another way of stating
the zeroth law is that every object has a certain
temperature, and when two objects are in thermal
equilibrium, their temperatures are equal. It is called the
ΔU = Q – W
where ΔU is the increase of internal energy of the
system, Q is the heat entering the system, and W is
the work done by the system.
The differential form of the 1st Law is
dU = dQ – dW,
where dU is an exact differential, because U is a
state variable, and both dQ and dW are inexact
differentials, since Q and W are not state variables.
SECOND LAW OF THERMODYNAMICS
The entropy of an isolated system never decreases;
ΔS ≥ 0,
or, at equilibrium, S → Smax.
For a reverse Examples of irreversible (real) processes:
i. temperature equalization;
ii. mixing of gases;
iii. conversion of macroscopic (ordered) KE to thermal (random)
ble (idealized) process only,
ΔS = 0, dS = dQ/T.
Zeroth Law of Thermodynamics
Two systems, separately in thermal equilibrium with a
third system, are in thermal equilibrium with each other.
The property which the three systems have in common is
known as temperature θ.
Thus the zeroth law may be expressed as follows:
if θ1 = θ2 and θ1 = θ3, then θ2 = θ3.
W = P(V2 – V1)
Calculating the work done in a reversible isothermal process requires the equation of state
of the system to be known.
Reversible isothermal process for an ideal gas (PV = nRT)
W = ∫PdV = nRT ∫dV/V = nRT ln(V2/V1).
In both cases, the work done by the system equals the shaded area under curve.