JEE · Physics · Thermodynamics & Kinetic Theory doubts
14 doubts found
What does “First law of thermodynamics” actually mean in Thermodynamics & Kinetic Theory, and why does it matter for JEE?
energy conservation for gases: ΔU = Q − W, where W is work done BY the gas.
I keep getting “First law of thermodynamics” questions wrong in Thermodynamics & Kinetic Theory. What's the trap?
getting the sign of W wrong (work done by vs on the gas).
What does “Internal energy” actually mean in Thermodynamics & Kinetic Theory, and why does it matter for JEE?
the total microscopic energy of a system; for an ideal gas it depends only on temperature.
I keep getting “Internal energy” questions wrong in Thermodynamics & Kinetic Theory. What's the trap?
thinking internal energy depends on pressure or volume for an ideal gas.
What does “Second law of thermodynamics” actually mean in Thermodynamics & Kinetic Theory, and why does it matter for JEE?
heat flows spontaneously from hot to cold, and no engine can be 100% efficient.
I keep getting “Second law of thermodynamics” questions wrong in Thermodynamics & Kinetic Theory. What's the trap?
believing you can fully convert heat into work in a cycle.
What does “Kinetic theory of gases” actually mean in Thermodynamics & Kinetic Theory, and why does it matter for JEE?
gas pressure comes from molecular collisions, and average molecular KE is proportional to absolute temperature.
I keep getting “Kinetic theory of gases” questions wrong in Thermodynamics & Kinetic Theory. What's the trap?
using Celsius instead of Kelvin in gas relations.
What is the difference between isothermal process and adiabatic process?
Isothermal keeps temperature constant (ΔU=0, heat exchanged); adiabatic exchanges no heat (Q=0, temperature changes).
What is the difference between heat and temperature?
Heat is energy in transit due to a temperature difference; temperature measures the average kinetic energy of molecules.
What is the difference between C_p and C_v?
C_p (constant pressure) exceeds C_v (constant volume) because at constant pressure some heat also does expansion work.
When do I use ΔU = Q − W in Thermodynamics & Kinetic Theory, and what does it mean?
first law: change in internal energy from heat and work.
When do I use PV = nRT in Thermodynamics & Kinetic Theory, and what does it mean?
ideal-gas equation of state.
When do I use C_p − C_v = R in Thermodynamics & Kinetic Theory, and what does it mean?
Mayer's relation between molar heat capacities.