How is heat transferred by convection?
In this session, you turn your attention from what heat transfer is, to how heat is transferred from hotter objects to colder objects.
In fluids, such as water and air, heat can be transferred by the movement of the substance itself - by convection. You might have thought about how ocean currents carry water around the Earth without considering how they carry heat. Heat transfer by ocean currents is one of the subjects under scrutiny by scientists concerned about the possible effect of global warming on climate change. While ocean currents are very complicated systems, and they're not easy to investigate, you can grapple with the same basic physics in an everyday glass of water.
This Week's Plan
Your challenge this week is to use convection to cool hot soup (or water) as quickly as possible. But first you'll take a closer look at convection in a video of ice melting in a glass of ice water.
Then you'll design and implement a test to compare two different strategies to cool hot soup using heat transfer by convection.
Although we’re focusing just on convection in this session, convection is invariably acting together with other modes of heat transfer (e.g., conduction, radiation, and evaporative cooling). In coming weeks you'll be sorting out their relative contribution to the phenomena involving heat and temperature that are all around you.
- Understand how heat is transferred by convection
What you need
- Temperature probes
- Coffee cups
- Hot water
- Everyday household materials (e.g., fan, spoon, cold water bath)