Area under a υ -1 graph represents a physical quantity which has the unit
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Answer:
The first law of thermodynamics states that the heat energy (Q) supplied to a system is equal to the sum of the change in internal energy (ΔU) and the work done (W) by the system. It can be represented as:
Q=ΔU+W
A positive Q is a heat transfer into the system and a negative Q is a heat transfer away from a system.
ΔU is the change in internal energy. For an ideal gas, as the internal energy is due to the kinetic energies of the molecules, the temperature only depends on the internal energy. Therefore an increase in the internal energy of a system results in an increase in temperature of the system.
A positive W is the work done by the system such as during the expansion of a gas and a negative W is the work done on the system such as during the compression of a gas.
All these quantities are expressed in joules (J).
WORK DONE BY IDEAL GAS
In an ideal gas, no forces of attraction act between gas molecules therefore they possess no molecular potential energy. This means that the temperature depends only on the internal energy (U) which in turn depends on the kinetic energy of the molecules.
To change the internal energy of a gas, work must be done or heat transfer must occur. For a tube of gas at pressure p in a piston:
piston_work
The force applied on the piston by the gas is equal to pA where A is the cross sectional area of the piston.
If the gas is allowed to expand slightly without a significant change in the pressure, the piston will move a distance Δx. This results in a change in volume equal to AΔx.
As the work done is equal to the force multiplied by the distance moved:
W=FΔxW=pAΔxW=pΔV
Explanation:
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