FREE GIVEAWAY FOR SEWARD STUDENTS

Seward Students Only: surface tension demonstration.

I have a limited number of Japanese 1-Yen coins. A Japanese Yen is currently worth about 1.2 US cents. Japanese people use these coins to pay sales taxes. I believe it costs the Japanese government more than 1 Yen to make each of these coins, but the Japanese people insist that they be made, so they can pay their sales taxes with them.

The Japanese 1-yen coin has the unique quality that it can "float" on water. It doesn't actually float, it is supported by surface tension.

Amaze your friends and family!

The Japanese 1-Yen coin is deliberately made to have exact metric values. Its diameter is exactly 2 centimeters, so its radius is exactly 1 centimeter. Its mass (weight) is exactly 1 gram. The thickness of the rim is 1.5 millimeters (0.15 centimeters) but it is stamped so the average thickness is 1.18 millimeters (0.118 centimeters)

Compute the volume of the Japanese 1-yen coin: use pi x (r squared) x average thickness: use the centimeter values.

Your result should be in cubic centimeters: please round to three decimal places.

Divide the mass (1 gram) by the just-computed volume: you should get a density in grams per cubic centimeter that exceeds 1.0, so the Yen should sink. (Please round the computed density to two decimal places). Incidentally, the density of a US penny is more than double the density of a Japanese Yen. Pennies won't "float;" they are too heavy for surface tension to support them.

But, if you carefully place the 1 Yen coin on the surface of a glass, cup, or bowl of water, it will appear to float; it is supported by the surface tension of water.

A subsequent blog will include some pictures of Japanese 1-yen coins "floating."

How to get your free Japanese 1-yen coin:

With  permission of your parents, parent, or guardian, go to this blog http://sewardmath1.blogspot.com

The blog accepts comments.

Make a comment: this should include your name, your Seward home-room teacher's name or, for middle-school students, your math teacher's name. Also include your calculations of the volume and density of a Japanese 1-yen coin.

The first thirty students to make a complete comment (name, teacher's name, volume & density) will get a free Japanese 1-yen coin. It will be delivered to the mailbox of your home-room teacher's mailbox or, for middle-school students, your math teacher's mailbox on the first school day following your comment.

To get a notice of additional posts to this blog, with permission of your parents, parent, or guardian: email me (stephen dot margolis at gmail dot com - replace "dot" and "at" with their usual symbols) your email or address or the the email address of your parents, parent, or guardian (the person or persons who receive your report card). If you do this, I will also verify that your calculations are correct. Use a calculator for these calculations. If you don't have a calculator, send me an email and I will give you one (to keep), if I haven't already. Seward Students Only!

As stated above, a subsequent blog will include some pictures of Japanese 1-yen coins "floating."

Computer security: I gave my email address in the strange form above because there are web crawlers: bots that search the internet for email addresses and then use these for evil purposes. The bots are dumb: they are looking for my.name@someplace.com.
 -