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important concepts and formulas in heat and thermodynamics

BIBIN N , 7 Years ago

Grade 12

2 Answers

Sanju

Last Activity: 7 Years ago

Heat is a form of energy that gets transferred from one medium or object to another medium/object.

Suppose if we a colder body and a hotter body and if it brought in contact, the heat gets transferred from the hotter body to colder body until the system of hotter & colder attains equilibrium. Here the heat lost by a body will be equal to heat gained by the body.

The amount of heat lost or gained by the body is, Q = m*c* dt

Here m is the mass of the object, c is the specific heat capacity and dt is the change in temperature.

Heat can be transferred in 3 ways: Conduction in solid objects, convection in liquids or gases and radiation.

Heat Capacity- It is defined as the heat required by a body to raise its temperature by 1K.

Specific Heat Capacity- It is the heat required to raise the temperature of 1 kg of mass by 1K. It is denoted using the letter ‘c’.

Specific heat capacity, c = Amountof heat given / [Mass * Increase in temperature]

Unit of specific heat capacity is J Kg^-1 K^-1

Sanju

Last Activity: 7 Years ago

Latent heat of fusion, L_f is the amount of heat absorbed by 1kg of solid to change into its liquid state at its melting point without change in temperature.

Latent heat of vapourization, Lv is the amount of heat absorbed by 1 kg of liquid to change into its gaseous state at its boiling point without change in temperature.

For problems with L_f and L_vuse the equation Q = m L_f or Q = m L_vto find the heat.

Thermodynamics:- It is the branch of physics which deals with process involving heat, work and internal energy. Thermodynamics is concerned with macroscopic behavior rather than microscopic behavior of the system.

Open system- exchange energy & matter with its surrounding.

Closed system-exchange energy across the boundary and doesnt exchange mass.

Isolated system-Wont exchange energy and matter with its surrounding.

Laws of theremodynamics

Zeroth law: If 2 bodies are in thermal equilibrium with a 3^rd body, them they are also in equilibrium with eachother.

First law: Also known as Law of Conservation of Energy. This law states that energy can neither be created not destroyed. It can only be transferred from one form to another.

There is another definition for first law of thermodynamics. “If the quantity of heat supplied to a system is capable of doing work, then the quantity of heat absorbed by the system is equal to the sum of the increase in the internal energy of the system, and the external work done by it.”

dQ = dU + dW -------------------> [ First law of thermodynamics]

dQ- the quantity of heat absorbed by the system, dU-change in internal energy and dW- external work

Second law: It states that the entropy of any isolated system increases always.

Entropy: It is the measure of disorder or randomness in the system.