I always wanted to try this (put dry ice in water) and last year I got the opportunity. When I bought some meat from Donald Russell it was delivered packed in dry ice (frozen CO2) i.e. solid carbon dioxide. This dry ice was used to keep the meat cool in transit. The meat and dry ice are transported in a polystyrene box which provides lots of insulation. However the heat does percolate a package like this and the dry ice sublimates, but usually there is some left on arrival. If not the meat temperature may rise too high. So I had a source of dry ice.
The first thing I wanted to do as soon as the meat was stored in a cool place was put the dry ice in water and watch it bubble away and the vapour flow out and down the side of the container. I caught it on video below:
It seems the Google job interview process requires a problem to be solved. I’ll take this hourglass problem, “Using only a four-minute hourglass and a seven-minute hourglass, measure exactly nine minutes.”
Solution Principle: Use one hourglass to measure out a smaller amount of time on the other hourglass. Repeat until you have the correct time periods stored in each hour glass such that when you add their times together by turning the second one up when the first finishes you get the correct total time of nine minutes. Continue reading “Google’s Employment Applicant’s Hourglass Problem”
NOTE: The article quotes, “….with the blackness of space and the bright curve of Earth providing a stunning backdrop.” However, if you watch the video carefully you will see as the balloon ascends and the horizon moves across the scene that the curvature of the earth varies from being convex to concave. This suggests to me that the camera lens has a lot of distortion and so it cannot be relied upon to give a good impression of the curvature of the earth.
Doesn’t paper folded enough times create a stack that reaches to the moon? Well it doesn’t here. However you would need a suitcase to carry it around if you wanted to protect yourself against being taken short. (It is toilet paper after all.) The students at St. Mark’s School in Southborough, Massachusetts asked how many times can you fold paper? They went on to break the record. See below:
My mentor drAnalog has advised me how to use Google Analytics to produce statistics of site visits. The analysis has thrown up some interesting results and from them I have concocted a Brain Teaser for your delight. Sorry no prizes given but you have the satisfaction of taking part.
My Brain Teaser
Some Derby people made 21 visits to this blog using an unspecified number of computers which we have to assume kept the same settings for each visit they made and hopefully used the same service providers each time.
13 visits were made using Internet Explorer, 6 using Google Chrome and 2 using Firefox browsers.
16 visits were made with Windows PC’s and 5 with Mackintosh computers.
18 visits were made via btcentralplus.com, 2 via ntl.com and 1 via virginmedia.com (service providers).
18 visits were made using 24bit colour and 3 using 32 bit colour systems.
8 visits used 1920×1200, 7 used 1366×768, 4 used 1280×800 and 2 used 1680×1050 screens.
19 visits use Flash version 11.1 r102 with Java support and 2 use Flash version 10.0 r32 without Java support.
What was the minimum number of COMPUTERS needed to make the 21 visits to the blog?
I suspect there might be enough data to deduce the answer but I can’t guarantee it.
Answers posted in comments will be seen by others.