AboutDan Fink Expertise Though my experience is mostly in the fields of electricity, magnetism, and physics, I have a broad science background. My career is in the field of alternative power sources -- solar, wind, water and battery power. But any questions about electricity, magnetism, energy conservation, power generation, electric motors, and even general physics are very welcome--especially from kids. They ask the best questions of all! I pride myself in answering science questions accurately, with ideas for SAFE, easy experiments that kids can perform by themselves--and that let them prove the answers to their own satisfaction. I think science should be fun, and available to everyone, regardless of age.
Experience I have volunteered in our local public schools for 5 years. I currently make presentations at our schools about electricity and magnetism, with a focus on solar, wind, water and other alternative power sources. I try to demonstrate at our schools how easy it is to make electricity, with simple devices using spinning magnets and coils of wire--powered by wind, water, bicycles, gerbils...etc. And of course solar panels! I am the webmaster of Otherpower.com, an alternative energy website. I have lived 10 miles from the nearest power pole for 11 years--I make all my own electricity from scratch with sun, wind and water.
Expert: Dan Fink Date: 1/22/2008 Subject: ice thawing rate
Question QUESTION: Mr. Fink,
A while back you answered the question below. I am doing a similar experiment. What we both are asking is --Which will thaw faster - ice made from hot water or ice made from cold water? Can you help?
Thank you,
Jordan
Mr. Fink,
I'am a fifth grader. Last year I did a science project to see which would freeze faster hot or cold water. This year I figured I would see which would melt faster hot or cold water. Will the water molecules play a role in this experiment like it did with last years' experiment? I would be very greatful for any information or websites that would help me with my research. Thank you for your time.
Taylor
Get the answer below
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Answer
I'm not quite understanding your question.....
>>This year I figured I would see which would melt faster hot or cold water.
water doesn't melt. Do you mean evaporate? Or whether hot/cold water makes ice melt faster?
In any case, let me know and I'd be happy to help.
There are some *really* bizarre things that go on with freezing and melting ice. Right at the freezing point, things are constantly melting and re-freezing. Just to get you started, here's a great explanation I just came across that shows most elementary school textbooks are wrong about how ice skates reduce fricton. http://www.amasci.com/miscon/miscon4.html#ice
Melting and freezing are really strange. I hope you have fun with your project!
DAN
ANSWER: Hi Jordan -=- it's a question that always gets confused! Hot water ALWAYS takes more time to freeze, because you have to remove more heat energy from it until it reaches the freezing point. Cold water always freezes faster--there's less heat ot begin with. The confusion comes because the question is sometimes phrased:
"Does boiled (NOT boilING) water freeze faster then tap water?"
TO which the answer is YES....because boiled water has more impurities removed. However, it's almost impossible to make that experiment work outside a laboratory because boiled water has only a few impurites removed -- even with distilled water it s hard to make it work. You can demonstrate it by comparing how long it takes for really salty water to freeze vs boiled water, though.
DAN
---------- FOLLOW-UP ----------
QUESTION: But which will THAW faster? And why? If I freeze water that was 40 degrees when I put it in the freezer and I took water that was 180 degrees when I put it in the freezer and let them BOTH freeze solid, which should THAW faster and why???
Answer Hi Jordan -- now I understand. Both will thaw at exactly the same rate, because the heating earlier didn't do anything to change the composition of the water. However---distilled water or boiled water will thaw a tiny bit faster than tap water, becuase by boiling or distilling you've made the water more pure. DAN
