Warm-Up True or False: Heat travels from colder objects to warmer objects?
Thermal Energy Transfer: Conduction, Convection & Radiation
Heat always moves from a warmer place to a cooler place.
Place your hand on your desk… Does your desk feel hot or cold? Now take your hand off your desk. Can you feel the warm spot where your hand was? This is the heat your desk took from you!!!
After switching class periods, have you ever sat in a chair that felt warm??! Ewww! Why do you think this chair felt warm when you sat on it?
Think about this… If a cup of hot coffee were left sitting in your kitchen at room temperature, what would happen?
The cup of coffee will cool until it reaches room temperature. The Coffee’s heat moved into the air.
If a red popsicle were left sitting in your kitchen at room temperature, what would happen?
The popsicle will melt and then the liquid will warm to room temperature. The heat from the surrounding air moved into the popsicle.
The transfer of heat by direct contact of objects.
Remember that gross WARM chair you sat on in your other class???! The person sitting in the chair before you transferred his/her heat to the cold chair. This is an example of Conduction because the heat transferred with direct contact! Because the chair is plastic and is an insulator … it took a LONG time for that person to sit in that chair to make it warm!
The transfer of heat by electromagnetic waves through empty space.
Radiation can travel through a vacuum True/False Radiation requires particles to travel True/False
Have you ever had a sunburn? How can you get burned from the suns heat if you are not in direct contact with the sun?
Radiation does not only come from the sun! Have you ever sat too close to a campfire while cooking marshmallows– enjoying the warmth- - only to notice that your skin is really warm?
Other examples of RADIATION 1.Fire 2.Heat Lamps 3.Sun
The transfer of heat by density changes in a fluid that causes motion.
Liquids and Gases are both fluids! Fluids are a substance whose molecules move freely past one another and that has the tendency to assume the shape of its container; a liquid or gas. What is Fluid?
What happens to the particles in a fluid (liquid or a gas) when you heat them? The particles spread out and become Less Dense. Cool Warm
Because the warmer fluid is less dense and the cooler fluid is more dense… The warmer fluid will rise up The cooler fluid will sink down Warm Cool
Have you ever… …noticed that the air near the ceiling is warmer than the air near the floor? Warmer Water Colder Water …or that water in a pool is cooler at the deep end?
Why does hot air rise and cold air sink? Cool air is more dense than warm air, so the cool air ‘falls through’ the warm air. Now that you know about Convection…
Identify the 3 types of heat transformation:
Multiple types of heat transfer can happen at the same time. What 2 types of heat transformation you see taking place below?
Convection & Conduction
Which of the following is not a method of heat transfer? A.Radiation B.Insulation C.Conduction D.Convection
In which of the following objects are the particles closest together and most dense? A.Cold B.Cool C.Warm D.Hot
How does heat energy reach the Earth from the Sun? A.Radiation B.Conduction C.Convection D.Insulation
Which of the following is the best conductor? A.Fabric B.Plastic C.Wood D.Iron
Which of the following is the best insulator? A.Copper B.Iron C.Wood D.Glass
Heat transfers from...? A.Hot to Cold B.Cold to Hot
If you touched a hot pan, this heat transformation you felt is called... A.Radiation B.Conduction C.Convection D.Insulation
B A C Where in this picture do you see Conduction?
B A C Where in this picture do you see Radiation?
B A C Where in this picture do you see Convection?