Physics Class 3 Flashcards
Heat vs Temperature
Heat is the transfer of non-mechanical energy between system & environment
- extensive property: depends on mass of material
Temperature is measure of average internal thermal energy of system
- intensive property: like density or colour
When does the temprature increase?
When you change the phase
Zeroth Law of Thermodynamics
When 2 substances are in contact, heat transfers between them until they achieve the same temperature (thermal equilibrium)
3 Modes of Heat transfer
- Conduction - heat transfer through solids in contact
- Convection - heat transfer through fluid circulation
- Radiation - heat transfer by emission/absorption of electromagnetic energy
First law of thermodynamics
Internal energy of a closed system depends on how much heat energy is transferred into system & how much work system does on its surroundings
ΔE = Q - W
Ideal Gas Law
PV = nRT
Isochoric
constant volume
ΔV = 0
ΔE = Q
Isobaric
Constant pressure
ΔP = 0
ΔE = Q - PΔV
Isothermal
Constant temperature
ΔT = 0
Adiabatic
No heat transfer
ΔQ = 0
Pressure
Distribution of force over an area
Formula: P = F / A
Units: N/m^2 = Pa (pascal)
1 atm = 100 kPa = 1000 Pa = 760 torr = 760 mmHg
Second law of thermodynamics
Entropy of an isolated system either stays the same or increases during any thermodynamic process
What happens to entropy of closed system?
It can decrease if the entropy of its surrounding environment increases by a greater amount because it exchanges energy with the outside environment
What kind of system is the human body?
Open system because it exchanges ENERGY and MATTER with its outside environment
Density
Formula: ρ = m/v
Units: kg/ m^3
