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Gram specific heat : The heat required to raise the temperature of one gram mass of a body through 1ºC (or 1 K) is called gram specific heat of the material of the body.

specific heat, c = Q/mΔT

Units : Calorie/gmºC (Practical), J/kg K(S.I.) 

Dimension : [L²T^–2θ^–1] 

(1) Thermal capacity : It is defined as the amount of heat required to raise the temperature of the whole body (mass, m) through 1ºC or 1 K. Thermal capacity = m c = µC = Q/ΔT

Dimension : [ML²T^–2θ^–1], 

Unit : call ºC (practical) Joule K (S.I.)

(2) Water Equivalent : Water equivalent of a body is defined as the mass of water which would absorb or evolve the same amount of heat as is done by the body in rising or falling through the same range of temperature. It is represented by W. 

If m = Mass of the body, c = Specific heat of body 

∴ Water equivalent (W) = mc gm 

The energy associated with configuration and random motion of the atoms and molecules with in a body is called heat. 

(1) Units : Joule (S.I.) and calorie (Practical unit) 

(2) The ratio of work done (W) to heat produced (Q) is constant. 

W/Q = J or W = JQ

J is called mechanical equivalent of heat and has value 4.2 J/cal. 

1 calorie = 4.186 Joule = 4.12 Joule 

(3) Heat is a path dependent and is taken to be positive if the system absorbs it and negative if releases it.

Temperature is defined as the degree of hotness or coldness of a body. Heat flows from higher temperature to lower temperature. 

Two bodies are said to be in thermal equilibrium when both the bodies are at the same temperature. Temperature α kinetic energy [As E = 3/2 RT]

The Kelvin temperature scale is also known as thermodynamic scale. The S.I. unit of temperature is kelvin and is defined as (1/273.16) of the temperature of the triple point of water. The triple point of water is that point on a P–T diagram where the three phases of water, the solid, the liquid and the gas, can coexist in thermal equilibrium. 

To construct a scale of temperature, two fixed points are taken. First is the freezing point of water, it is called lower fixed point. The second is the boiling point of water, it is called upper fixed point.

Gases have no definite shape, therefore gases have only volume expansion.

Total work done by gas, W_Total​ = W_AB ​+ W_BC ​ + W_CA​

∆Q = ∆U + W (from I law of thermodynamics)

or, ∆Q = nC_v∆T + ∆W  (∵ ∆U = nC_v∆T)

if system has constant temperature inspite of heat supplied then supplied then

∆T = 0 and ∆Q = ∆W. It means heat supplied (∆Q) to the system is used in doing work (∆W) against the surroundings.

The mechanical energy can be completely and continuously converted into heat. Bu the reverse is not possible.

A Carnot engine is an ideal heat engine form the following points of view:

(i) There is absolutely no friction between the walls of cylinder and piston.

(ii) The working substance is an ideal gas.

In a real engine, these conditions cannot be fulfilled and hence no heat engine working between the same two temperatures can have efficiency greater than than of carnot engines.

Yes, it can be done with the help of an external agent.

On the temperature of source of heat and the sink.

We know that, 

η = \(1-\frac{T_2}{T_1}\) 

On increasing the temperature of sink (T₂), the efficiency of the Carnot engine will decrease.

No, it is an ideal engine which practically not possible to construct.

No, the coefficient of performance of a refrigerator decreases as its inside temperature decreases.

If the temperature of sink is zero kelvin.

No. As the inside temperature of the refrigerator decreases, its coefficient of performance decreases.