If the amount of heat given to a system be 85 J and the amount of work done by the system be 35 J, then the change in the internal energy of the system is
If the amount of heat given to a system be 85 J and the amount of work done by the system be 35 J, then the change in the internal energy of the system is
The correct option is A 50
From first law of thermodynamic, △U=q+w
where q = Heat entering the system
w = Work done on the system
△U = Change in Internal energy
Given, q = 85 J, w = -35 J
⇒△U=85−35=50 J
Theory :
Laws of Thermodynamics: There are four laws of thermodynamics.
-
Zeroth law
-
First law
-
Second law
-
Third law
Zeroth Law of Thermodynamics: According to this law, if body A is in thermal equilibrium with body B and body B is in equilibrium with another body C then A and C are also in thermal equilibrium with each other.
Thermal Equilibrium: Temperature may have different values at different places but if it remains constant with time then it is called thermal equilibrium.
First Law of Thermodynamics: It states that
-
Energy can neither be created nor destroyed
-
It can only be transferred from one form to another.
-
The total energy of an isolated system is always conserved.
The internal energy of the system changes only when the exchange of internal energy happens with the surroundings. If the exchange of internal energy happens due to temperature difference then it is called heat. Otherwise, it is called work.
∴ ΔU=q+W
Where q = Heat given to the system
W = Work done on the system
This expression is the mathematical form of the first law.
Note: d represents a very small change while Δ represents the appreciable change in any quantity.
From first law of thermodynamic, △U=q+w
where q = Heat entering the system
w = Work done on the system
△U = Change in Internal energy
Given, q = 85 J, w = -35 J
⇒△U=85−35=50 J
Theory :
Laws of Thermodynamics: There are four laws of thermodynamics.
-
Zeroth law
-
First law
-
Second law
-
Third law
Zeroth Law of Thermodynamics: According to this law, if body A is in thermal equilibrium with body B and body B is in equilibrium with another body C then A and C are also in thermal equilibrium with each other.
Thermal Equilibrium: Temperature may have different values at different places but if it remains constant with time then it is called thermal equilibrium.
First Law of Thermodynamics: It states that
-
Energy can neither be created nor destroyed
-
It can only be transferred from one form to another.
-
The total energy of an isolated system is always conserved.
The internal energy of the system changes only when the exchange of internal energy happens with the surroundings. If the exchange of internal energy happens due to temperature difference then it is called heat. Otherwise, it is called work.
∴ ΔU=q+W
Where q = Heat given to the system
W = Work done on the system
This expression is the mathematical form of the first law.
Note: d represents a very small change while Δ represents the appreciable change in any quantity.
