NEWSLETTER MATERIAL

Brain Teaser Challenge by Butch Shadwell

Brain Teaser Challenge Solution - August 2009 Butch Shadwell

Harvesting hydrogen from the sea was the subject. “We all know that deuterium is found in much higher concentrations in the sea than in the atmosphere. Perhaps the heavier molecules find it harder to make the transition from liquid to gas phase on the surface, so most of the evaporation is of the lighter isotopes. So the problem today is - how big a container do I need to hold 1 mole of H2 at STP?”

In this problem, fact that the gas is deuterium is not relevant at STP. The answer is approximately the same for a mole of any gaseous compound. Remember pV=nRT, where n is the number of moles of the gas in question and R is a proportionality constant that varies depending on the units selected for the other three variables. For p in atmospheres, V in liters, and T in degrees Kelvin, R = 0.0821 L atm/K mol. Since p and n equal 1, V = R * T or V = 0.0821 * 273, or 22.39 liters. But I bet you already knew that.

Brain Teaser Challenge – September 2009 Butch Shadwell

Little Schlomo had nothing on his mind as he rolled the wheel down Pearl Street with his stick. The sound this perfect circle made as it rumbled along, drew his thoughts away from here and now. It was 1889, and for a ten year old in New York, life was lived in the street, and things were hard. Uncle Lenny, who had been living with his family for as long as he could remember, was sure his ship would come in any day now. Even though he knew it was rubbish, sometimes Schlomo would enjoy listening as his uncle would explain his latest get rich quick scheme. It was on a Tuesday, as he heard his Uncle Lenny describe his new electric light business. As you know, light bulbs were pretty expensive, about a dollar a piece, and they didn’t really last that long. Lenny’s idea was to sell folks lower voltage light bulbs which were a little cheaper and would last a little longer. He planned on buying transformers to reduce the voltage. What turn ratio did he need to run 25 volt bulbs? Hope you remember your electrifying history.

Reply to Butch Shadwell at b.shadwell@ieee.org (email), 904-410-9751 (fax), 904-410-9750 (v), 3308 Queen Palm Dr., Jacksonville, FL 32250-2328. (http://www.shadtechserv.com) The names of correct respondents may be mentioned in the solution column.