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Q & A: Physics Questions? Ask the Van

Physics Questions? Ask the Van

Question of the Day

"Would it be possible (at least in theory) to heat a small building using a heat pump, but using no energy to run the pump? It seems unlikely, but why not? I am familiar with the laws of thermodynamics. I know we are not supposed to be able to get work from a non-spontaneous process, like a heat pump. Say you used a Stirling engine to start the process. You could easily get five or ten times more thermal energy out than the energy used. Then you could use some of that energy to run the pump leaving the rest to heat the building. What am I missing here? This is a question about physics theory, not about engineering."
-Robert (age 66)

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About Us

8421 questions have been answered online since 1998 by volunteers from the Department of Physics at the University of Illinois' Physics Van outreach program. We've tried hard to make this the most reliable physics Q&A site on the Web, but no site is perfect, as we explain on this note. Our Baloney feature provides examples of how shaky many other sites are.

If you'd like to ask us a new question, not already covered, please read our answering guidelines first. We try to answer as many questions as we can, but it's not always possible to answer them all. Questions from kids are especially welcome.

Although we recommend not using our informal site as a cited reference, students who are in a rush and can't find a more proper peer-reviewed source can check our citation information section.

Questions from kids are especially welcome!