Energy, Heat and Work Flashcards
What is energy in thermodynamics?
Energy is the capacity to do work or transfer heat.
What is internal energy?
The total energy of a system due to molecular motion and interactions.
How is work defined in thermodynamics?
W = PΔV
Where
P: Pressure,
ΔV: Volume change.
How is heat defined in thermodynamics?
Heat is energy transferred due to a temperature difference.
What is the sign convention for heat and work?
Heat (Q): Positive if added to the system, negative if removed.
Work (W): Positive if done by the system, negative if done on the system.
How is specific work calculated during polytropic processes?
W = (P2V2 - P1V1) / (1 - n)
Where n is the polytropic index.
What are examples of energy transfer mechanisms?
Heat transfer.
Work transfer.
Mass flow (in open systems).
What are the modes of heat transfer?
Conduction: Through a solid.
Convection: Between a solid and fluid.
Radiation: Emission of energy as electromagnetic waves.
What is specific heat?
The amount of heat required to raise 1 kg of a substance by 1°C (measured in kJ/kg.K)
What is the physical interpretation of internal energy?
It represents the energy stored in the random motion and interaction of molecules.
What is enthalpy?
The property that represents the total energy of a system, including its internal energy and the energy required to displace its surroundings to make space for the system.
H = U + PV
Where
H : Enthalpy
U : Internal energy
P : Pressure
V : Volume
