HEAT thermal energy

Kinetic Theory of Matter States the following three points 1. Matter is composed of extremely small particles called atoms 2. These particles are in constant, random motion 3. The movement of the particles determines the phase of matter the substance is in

Matter/Energy Connection The warmer the object, the more kinetic energy it has The cooler, the lower the kinetic energy As you heat or cool something it changes its phase because it changes the kinetic energy

Thermal Energy Is actually the average kinetic energy of a system A system can be an object or the atmosphere in a room or... Anything

Temperature It is a way of telling how warm or cold something is It is, in actuality, a measure of the kinetic energy of the system So if we check the temperature in a room we are actually measuring the motion of the molecules and atoms in the atmosphere of the room

Temperature Scales Theoretically there is no upper limit to heat Matter will keep changing phases Until it reaches the plasma phase Stars are plasma, they have temperatures in the millions of degrees There is a limit to low temperature though

Absolute zero this is the theoretical temperature at which every bit of kinetic energy from the atoms and sub-atomic particles has been removed It cannot get any colder Absolute zero is equal to -273 C

What is heat? Heat is the thermal energy transferred from one object to another or thermal energy in transit Thermal energy flows from warmer to cooler objects until equilibrium is reached

What is cold? Cold is not a thing It is not a type of energy It is a lack of thermal energy or very low thermal energy Something feels cold to you because you are losing heat to it

Ice is cold because the particles of water have very low kinetic energy and the particles of your finger have a higher kinetic energy so, thermal energy transfers from you to the ice. You lose heat.

Laws of Thermodynamics First Law When heat is transferred it does so without a net loss or gain This means that whatever is lost from one place is gained in another

Second Law Heat never spontaneously flows from a cold substance to a hot substance Third Law No system can reach a temperature of absolute zero

Specific Heat Capacity This is defined as the quantity of heat required to change a unit mass of a substance by 1 C. Different substances have different capacities for storing thermal energy

Water has a very high capapcity for storing heat A lot of heat is needed to change the temperature of water Water also takes longer to cool

Specific heat equation Q = mcΔT Q = heat transferred m = mass c = specific heat ΔT = change in temperature (Tfinal – Tinitial)

Heat Transfer There are three types of heat transfer 1. Conduction When heat travels from the hot end of an object, through the length of the object, to the cooler end. This happens due to particles in the object heating up, colliding with particles next to them amd transferring energy

2. Convection Heat transferred by the motion of a fluid These are called convection currents Cooler things ae more dense, so they settle at the bottom. This forces warmer objects up, causing currents

3. Radiation This is when heat is transferred without a medium to travel through. It is neither conduction or convection. It is a form of electromagnetic waves This is how heat from the sun travels through the vacuum of space to get to earth The higher the frequency of the wave, the higher the energy transfer

Thermal Expansion This one is easy As objects heat up, their molecules move faster This leads to more outward movement The net result is an expansion of the heated object Objects contract when they cool off