Energy Transfer
What is the definition of Conduction?
A. When heat travels as electromagnetic waves through space or transparent materials, without needing direct contact.
B. When heat travels through direct contact, causing atoms or molecules to vibrate and collide, passing energy to neighboring particles.
C. When heat moves through the circulation of fluids.
B. When heat travels through direct contact, causing atoms or molecules to vibrate and collide, passing energy to neighboring particles.
A. A winter coat
B. A wool sock
C. A wooden spoon
D. A copper wire
D. A copper wire
What is kinetic Energy?
Kinetic energy is the energy to move.
Define temperature
Temperature is a measure of how hot or cold something is. This can be found by averaging the amount of kinetic energy in the sample.
What are molecules?
Molecules are atoms bonded together
Which of the following is NOT convection?
A. Boiling a pot of water
B. Turning the heat on in a cold room
C. Black asphalt heating up from the sunny day
D. An oven baking a cake.
C. Black asphalt heating up from the sunny day
Which of the following is NOT a conductor?
A. A metal pan
B. A metal prong of a plug-in
C. A cup of saltwater
D. Glass
D. Glass
What causes objects to have a higher temperature?
The movement of their molecules. The faster the molecule moves, the hotter the sample/object is.
Calculate the temperature of the sample:
1 3 5
2 4 5 1
3
How can you lower the temperature of a sample or object?
By placing something with less thermal energy (colder) next to it, so the thermal energy leaves the first sample and enters the colder object.
Define radiation.
When heat travels as electromagnetic waves through space or transparent materials, without needing direct contact.
solid
Draw two samples at equilibrium.
Calculate the temperature of the two samples
Sample 1 Sample 2
10 4 1 3 4 6
3 5 1 7 2 8
Sample 1: 4
Sample 2: 5
How does AC make a room cooler?
By lowering the speed of the molecules.
2. Claude is in the kitchen cooking and is going to stack one pan on top of another pan. The two pans are the same size and have the same number of molecules. The diagram above shows the pans now, before they touch each other. Use the information in the diagram to answer the question.
How does the temperature of the top pan compare with the temperature of the bottom pan now, and what will happen after the pans have been touching for a while?
The bottom pan is hotter. After the pans have been touching for a while, they will reach an equilibrium that is somewhere between the two original temperatures.
How do insulators work?
They stop thermal energy from transferring.
How does thermal energy transfer?
Thermal energy transfers in 3 ways:
Convection, conduction, and radiation
Thermal energy always moves from areas of high thermal energy (hot) to areas with less thermal energy (cold) by molecules colliding with each other.
Calculate the temperature of the two samples
Sample 1 Sample 2
6 6 3 1 5 6
3 9 9 6 3 3
Compare the temperature of the two samples
Sample 1: 6
Sample 2: 3
Sample 1 is hotter than sample 2.
How does AC make cities hotter?
By transferring the thermal energy that was in the room or house outside.
An architect is stacking pieces of plastic to make two columns in a model building. The diagram above shows the pieces of plastic before they touch each other. Use the information in the diagram to answer the question.
After they have been touching for a while, which of the two top plastic pieces will be cooler, and why?
A. The larger top plastic piece will be cooler than the smaller top plastic piece. It started with more total energy, so less energy had to transfer for both pieces in the stack to reach the same total energy.
B. The larger top plastic piece will be cooler than the smaller top plastic piece, because the energy that transferred to it was spread out over more molecules.
C. Both pieces will be the same temperature, because both of the bottom pieces had the same amount of energy to transfer and the molecules in the top plastic start with the same energy.
D. The smaller top plastic piece will be cooler than the larger top plastic piece, because less energy has to transfer for the molecules to reach the same temperature as the molecules of the bottom plastic.
B. The larger top plastic piece will be cooler than the smaller top plastic piece, because the energy that was transferred to it was spread out over more molecules.
Non-metals are insulators because ___________ easily through the structure.
Metals are conductors because ________ through the structure.
Thermal energy cannot move
Thermal energy can easily move
In some places, hot water from underground can shoot up into the air through a hole in the ground. When this happens, the ground surrounding the water increases in temperature. What happens to the molecules in the ground when the temperature of the ground increases?
A. More heat molecules combine with the molecules in the ground.
B. The energy of the molecules in the ground decreases.
C. The energy of the molecules in the ground increases.
D.The cold energy of the molecules in the ground decreases.
C
Nistu is cooking rice in a pot. When she leaves the pot on the stove for a while, the temperature of the rice increases. What happens to the molecules of the rice when the temperature of the rice increases?
A. The energy of the molecules in the rice increases.
B.The cold energy of the molecules in the rice decreases.
C. The energy of the molecules in the rice decreases.
D. More heat molecules combine with the molecules in the rice
A
What is HTST in pasteurization?
High temp short time.