Chapter 2 Flashcards
What does Internal Energy consist of?
- Kinetic Energy
of particles due to their RANDOM MOTION - Potential Energy
due to the INTERACTIONS BETWEEN PARTICLES
What does the Kinetic Energy consist of?
- Translational
- Rotational
- Vibrational (within particles)
What is temperature?
Measure of the average translational kinetic energy of the particles within a system, because, at any instant in time, the particles within a system will have a RANGE of speeds, THUS A RANGE OF KINETIC ENERGIES.
How do you convert Celsius to Kelvin
Add 273.15
When does water boil in Kelvin?
373.15
When does water freeze in Kelvin?
273.15
Difference between heat and temperature?
Heat is a measure of the TRANSFER OF THERMAL ENERGY
Temperature is the measure of the average translational kinetic energy of the atoms
Summarise Internal Energy
It describes the energy associated with the motion and interactions between particles in a system, AKA Thermal energy
What is the kinetic theory of matter?
ALL MATTER consists of particles that are CONSTANTLY MOVING in a RANDOM WAY
What is Thermal Equilibrium
When two systems have the same temperature, and there is no net heat transfer
What is heat?
The energy the flows between systems due to the difference in temperature
What is Heat written as and measured in?
Written as Q, measured in Joules since its ENERGY
What is conduction?
form of heat transfer between systems due to collisions between their particles
Conduction only occurs when…?
- The two systems are in direct physical contact
- The systems are at different temperatures
What does the heat transfer rate formula tell us?
It tells us that the heat transfer rate between 2 systems is directly proportional to their difference in temperature, as Q/T is directly proportional to the change in temp.
What happens to the rate of conduction if the area increases?
Also increases
Summarise what happens when 2 systems are in physical contact
Particles collide and exchange translational kinetic energy (temperature), and in each collision, the temperature is transferred from the particle with more temp to the one with less
Over time, energy transfers from the higher temp system to the lower temp system
Give an example of a good thermal conductor
pure metals, such as diamond (best) are good conductors of heat as they are closely packed together, and have free moving electrons thus collide more
Give an example of a good thermal insulator
air is a good insulator as the particles are more spaced out and they dont collide very often, meaning the heat transfer rate is very slow
How is heat transferred through convection?
As higher temperatures means that the particles have greater average kinetic energy, meaning that this additional kinetic energy results in the partciles being more SPACED OUT, DECREASING THE DENSITY OF THE MATERIAL.
The fluid with the higher density SINKS, DISPLACING the LESS DENSE FLUID, PUSHING the LESS DENSE fluid UPWARDS
When can convection occur?
Only in flowing substances (FLUIDS)
It can be natural or forced.
Summarise convection in a pot
The colder fluid is denser, so it sinks pushing up the hotter fluid. As the hotter fluid cools down after RISING, it TRANFERS HEAT TO ITS COOLER SURROUNDINGS, THUS increasing the density and thus falling to the bottom, this cycle keeps going as long as heat persists.
What is forced convection?
Fluid flow that transfers thermal energy where the heat itself does not drive the flow, meaning that ANOTHER energy source must drive the flow
What is thermal radiation?
Form of heat transfer that is due to the emission & absorption of energy as electromagnetic radiation
