Brain Teasers
All Jammed Up
Duffus came home one afternoon to find his wife in the kitchen making homemade jam. She had a few jars on the table, and was attempting to tape the vacuum hose on a lid, when Duffus arrived. "What are you doing, dear?" he asked, confused by the piles of twisted tape that clung to everything in the kitchen. Mrs. Redneck says that vacuum sealing the jars helps keep them fresher and tasting good longer. Duffus laughed as he put a large pot on the stove to heat up, then filled up the sink with water, took the vacuum and tape from his wife and said, "Let me show you how it's done, dear."
How was Duffus planning to vacuum seal the jars?
How was Duffus planning to vacuum seal the jars?
Hint
Think what happens when things get hot and when things get cold.Answer
Duffus took the lids off the jam jars and placed them in the hot water, which caused the jam to expand in the jar. When they were hot, he removed them, put the lids back on and placed them in the cooler water in the sink, which caused the jam to contract. Since the lid was sealed tight, the air pressure inside was less than the pressure outside the jar, which created a sort of vacuum-sealed effect.Hide Hint Show Hint Hide Answer Show Answer
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Well, to me it seems a bit better suited for Situation then Science. Science generally means something harder, while it's common knowledge that heat expands. Great job!
No matter how you slice it, heat expansion is science in action, tissue. I'm pretty sure I said this the first time this teaser was submitted, but the cooling water is an unnecessary step. If you just put the lids on the hot jars and let them cool to room temp, the final pressure will be exactly the same as when you cool the jars to below room temp and then let them heat back up to room temp. I like teasers of this nature that deal with basic chemistry or physics but don't get too technical. They test your "science instinct" instead of just testing whether you've taken the right physics class or not.
Why is this teaser in situation? It is better suited for science, as it only has one real answer, and doesn't need many questions to arrive at such.
i agree - science all the way, it's about the way that heat affects objects, it's got nothing to do with the situation.
i'm still wondering what duffus did with the vacuum cleaner though...
i'm still wondering what duffus did with the vacuum cleaner though...
why dont they just get a vacum sealer?
I though he was going to stick a small candle on top of the jam, light it, put on the lid, and let the candel use up the oxygen. But i'm beginning to think your method might be simpler. Nice one.
P.S. try this, take a shallow dish and cover the bottom with water. Then, take a small candle and light it on the dish. Cover it with a glass cup and see what happens!
P.S. try this, take a shallow dish and cover the bottom with water. Then, take a small candle and light it on the dish. Cover it with a glass cup and see what happens!
I dont get it ... in jam making I just know this kind of vacuum-sealing. Filling hot jam in the jars, seal them and let them cool down ... Cant imagine, that other sites fill cold jam in the jars ...
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