Jim and Joe
Science brain teasers require understanding of the physical or biological world and the laws that govern it.
Jim and Joe were close brothers until Jim graduated from Yale and became a renowned scientist who made millions. Not wanting to be outdone, Joe invited Jim over to a mansion that he claimed was his. He showed Jim many wonderful things inside the house one of which was a golden statue.
"This was a little gift from a friend of mine," Joe said, rapping on it with his fist, "It's made out of pure gold. See? Even my powerful fist can't make a dent in it."
"I have to say, this is all impressive," Jim admitted, "but I know this is all fake, Joe."
How did Jim know Joe was lying?
If Joe's statue was made of pure gold, it would've dented easily from Joe's fist. Pure gold scores only a 2.5 - 3 on the Mohs scale, and is easy to mold in your hands.
May 20, 2011
|Learn something new everyday! Good job on the teaser. |
May 20, 2011
|That was pretty easy but fun!|
May 21, 2011
May 23, 2011
|This was something good. |
Jun 02, 2011
|Easy but fun. |
Jul 27, 2011
|My hard pure gold cat is all truth.|
Oct 23, 2011
Jun 15, 2012
|I've known that since 2nd grade, which was when a friend of mine who is clearly above average IQ explained to the class that something could be metal AND soft, pure gold. |
Jul 12, 2012
|Overall, I loved the story, but I felt it was just a bit of a giveaway by stating "See? Even my powerful fist can't make a dent in it." Well done, but beware giveaways!!!|
Jul 28, 2013
|I know that pure gold is much softer than most metals. But is it really THAT soft that knocking on a large, solid statue would dent it? If I were to knock on a gold bar, would it dent that easily? I'm not saying it's wrong, because I really don't know; but I'm saying that I would be surprised if it's THAT soft.|
Oct 24, 2013
|It was pretty easy. I got it as soon as he said it was pure gold. |
Oct 13, 2016
|The Mohs Scale measures hardness in terms of scratch resistance, not malleability or deformation. Vickers measures hardness in terms of plastic deformation. Vickers strength of pure gold is about 30-34, which means you'd need about 34 kg of force per square millimeter to deform it. Casually "rapping" with your fist on a solid, pure gold statue with your fist would not be enough to "mold" or deform it. |
Besides, the word "pure" is not a true measurement of fineness in gold. If Joe had said his statute was 999.999 pure, he'd be lying as such purity is next to impossible to obtain. 100 percent pure gold doesn't even exist, not even in nature.
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