Presentation on theme: "Heat always flows away from a hot material to a cold material"— Presentation transcript:
1 Heat always flows away from a hot material to a cold material Heat TransferWhat is a heat?Heat always flows away from a hot material to a cold materialRemember, heat moves in predictable ways, from a high temperature to low temperature.
2 Hot objects in a cooler room will cool to room temperature. Heat TransferHot objects in a cooler room will cool to room temperature.Cold objects in a warmer room will heat up to room temperature.So that everything is in a state of equilibrium, meaning equal.
3 QuestionIf a cup of coffee and a red popsickle were left on the table in this room what would happen to them based on how heat moves? Why?
4 QuestionIf a cup of coffee and a red popsickle were left on the table in this room what would happen to them based on how heat moves? Why?The cup of coffee will cool until it reaches room temperature. The popsicle will melt and then the liquid will warm to room temperature.
5 Heat transfers in three ways: Conduction Convection Radiation Heat Transfer MethodsHeat transfers in three ways:ConductionConvectionRadiation
6 ConductionConduction is heat energy moving from a high-temperature object to a low-temperature object.Occurs in solids only.
7 ConductionWhen you heat a metal strip at one end, the heat travels to the other end.Conduction is the direct transfer of heat or energy from one molecule to another molecule by collision.
8 In solids, every atom is bonded to another atom In solids, every atom is bonded to another atom. If we apply heat to one part of a solid the atoms begin to vibrate.
9 The heated atoms vibrating causes atoms to collide. ConductionThe heated atoms vibrating causes atoms to collide.This passes the heat from one atom to the next.The energy spreads throughout all the molecules of the solid, and the temperature increases.
10 ConductionThis is why when a metal pot or pan is placed on a hot stove, the whole pan becomes hot, rather than only the bottom.
15 ConvectionWhat happens to the particles in a liquid or a gas when you heat them?The particles spread out, rise and become less dense.
16 Fluid movement Cooler liquids and gases s___. inkWarmer liquids and gases r___ up.ise
17 Water movementConvection currentHot water risesCooler water sinks
18 Convection CurrentThe water or air at the bottom heats up first causing it to expand. Since the warmed air or water has a lower density (it’s lighter) than the air or water around it, it rises up.At the top, the air or water cools, increasing its density, which causes it to sink back down to the bottom. This up and down movement eventually heats everything. The continual cycling is called a convection current.
19 Explaining Convection Convection currents cause the movement of magma within the earth.
21 Where is the freezer compartment put in a fridge? Cold air sinksWhere is the freezer compartment put in a fridge?Freezer compartmentIt is warmer at the bottom, so this warmer air rises and a convection current is set up.It is put at the top, because cool air sinks, so it cools the food on the way down.