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Q & A: Physics Questions? Ask the Van

Physics Questions? Ask the Van

Question of the Day

"Ok sorry about this one but I will give it a go. This interaction based on mass that we call gravity. Has studies been done on why the gravity attraction is reduced as a substance changes state from solid, liquid, gas? What am I driving at well we know mass changes as the energy is applied boiling water releasing water as steam. But what actually changes about the molecules that reduces the attraction. I realise they have more energy and electron orbits are increased. Sorry I am not clear myself and this may seem a little bit of a dumb question but I was wondering if this would give a handle on gravity."
-Dave S (age 44)

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8380 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.

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Questions from kids are especially welcome!