Thermal Energy Flashcards
What is Conduction?
Heat moves through solid materials (e.g. the walls of a cup
What is convection?
Heat moves through the air currents surrounding the cup
What is insulation?
Materials like foam or air gaps the slow heat transfer
What materials are cups made of and how do they affect heat transfer?
Explain how foam, paper, plastic would either retain heat or cold
What are some features of cups to slow heat transfer?
Double walls, air gaps, lids
How do double walls work for cups?
Creates a barrier that slows down conduction
How do reflective coatings help cup designs?
They reflect heat radiation away from the drink
How do lids help in cup design?
They minimize convection and evaporation
What are similar and different features that cold and hot cups share?
Similar- Insulation slows heat movement into or out of the drink and reflective coating can work to retain heat inside or repel it outside
Differences- materials like dark colored surfaces can absorb heat, which is helpful for keeping things hot but not keeping things cold
How do lids affect what happens to liquids in the cup?
Lids reduce heat transfer by slowing convection ad reduce evaporation
Where does the water on the outside of the cold cup come from?
Condensation, which is water vapor in the air cools when it come into contact with the cold cup, the cooling causes the water vapor to condense into liquid
This happens when the cup surface is lower than the dew point
How can we explain the effect of a lid on what happens to liquid over time? (2)
Minimizes evaporation which maintains the volume and temperature
Blocks heat transfer (convection) between the liquid and air
