Temperature is defined as the average KE of the particles. Depends on average speed only of particles (atoms or molecules)
A bucket of water at 50o has the same temperature as a cup of water at 50o
Average KE and the mass of the particles Depends on speed and the mass of the particles.
A bucket at 50o has more thermal energy than a cup at 100o
Bucket of $50 bills has more money than a cup of $100’s.
While the particles are going faster in the cup, there are so many more in the bucket.
Transfer of energy between objects that have different temperatures.
The direction of heat flow depends on temperature. From hot objects (more energy) to cold objects (less energy).
The speed of the heat flow depends on ...
Gas molecules collide with each other and their surroundings. Within a sample of gas we find that:
there is a large number of gas molecules (N) moving in random directions and a variety of speeds.
the particles are far apart, with the separation distances being vast compared to the diameter of each particle.
the particles obey laws of mechanics. They attract each other, but we ignore this since the speeds and KE are huge (electrostatic attraction <<< KE motion).
collisions with each other and container walls are assumed to be perfectly elastic. Conservation of momentum and KE.
The higher the temperature the faster the molecules move. The particles vary in speed, so we can only measure an average.
Half will be going faster and half slower than the average.
Boyle’s Law:
Charles’ Law:
Combined Law:
http://www.thephysicsaviary.com/Physics/Programs/Labs/MechanicalEquivalentOfHeatLab/
Think of the amount of energy in universe as constant. But, energy can be added to or subtracted from a system (engine, etc.). Energy comes from or goes to the greater universe (environment). Energy can transfer between systems. A ball colliding with another can transfer energy to that ball. Energy can change forms. If you calculate potential energy that energy can change into kinetic energy, electrical energy, thermal energy, etc.
All matter has some amount of energy. Objects feel warm to the touch (internal energy: due to heat content or thermal energy of the object) caused by vibration of atoms that make up the object. If energy is added to an object it can start moving or become hotter. If energy is subtracted it can slow down or become colder.
Heat transfer occurs in one of three ways.
Conduction: Objects touch transferring energy.
http://www.thephysicsaviary.com/Physics/Programs/Labs/HeatTransferGasesLab/
Convection: Fluids (gases & liquids) carry heat as they flow. Hot air or water rises. Convection currents.
DEMO: Convection box
Radiation: Electromagnetic radiation, as in infrared frequencies of light. Why does a thermos have an inner container separated from the outer by a vacuum? Why is the inside reflective?
http://www.thephysicsaviary.com/Physics/Programs/Labs/RadiantEmission/