Engineering Question #583

Rena, a 12 year old female from Thornhill asks on January 22, 2002,

For school I need to know about natural convection and forced convection. I need to know the difference. I have looked everywhere but no imformation is given. Will you be able to tell me what they are and how they affect our world? How do they help it? If you know any sites with pictures can you tell me those too?

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The answer

Barry Shell answered on January 22, 2002

For questions like this, go to and type in words like: natural convection and forced convection.

I just took those very words from your question, put them in google, and in the first results, found the answer:

The temperature of the solid due to an external field such as fluid buoyancy can induce a fluid motion. This is known as "natural convection" and it is a strong function of the temperature difference between the solid and the fluid. Blowing air over the solid by using external devices such as fans and pumps can also generate a fluid motion. This is known as "forced convection".

What this means is: Say you have a bowl of hot soup. If you leave it alone, it will cool off by natural convection because the air around it is cooler than the soup. If you blow on it to cool it off, that is forced convection.

To find pictures, you also go to and put in the same words, but click on the word "Images". Then pictures will come for the thing you want. It's just amazing. Good luck. Use google all the time.

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