Maddenation
Clocks and power failures
As you know, David emplys “bell ringers” in his teaching of science. Bell ringers are little puzzles given before class begins that the class can work on as they take their seats. David has shared a number of them with me, and I have given him a few ideas too. Today, I was passing on a puzzle from Ask Marilyn and it occurred to me that Kathleen is also teaching physics in California this year. So I started an email to both of them, when it occurred to me that Karina like puzzles too. Then I thought of Maddenation and here I am.
The first problem is a dad original that I thought of years ago after a power failure in the house. The digital alarm clock on my side of the bed reset to 12 a.m. when the power returned, and flashed on and off to indicate that the power had been off.
Power failure problem
Diane returns home from her job at 5:30 p.m. to find her digital clock flashing, with the time at 6:27 a.m. Her “traditional” electric clock (with hands) in the kitchen reads 3:50. What time did the power failure occur and how long did it last?
Answer
Digital clock reads 6:27 AM
Traditional clock reads 3:50 PM
Digital clock says power came back on 6 hr 27 min ago.
Traditional clock says power was off 5:30 - 3:50 = 1:40.
So, power came back on at 11:03 a.m.
Therefore, power went off 1:40 earlier, or 9:23.
power off 9:23 AM
power on 11:03 AM
duration 1:40 AM
Diane returns 5:30 PM
Comments
David • 08/03/03 • 8:45 PM:superb Dad! i’ve almost got it finished and looking pretty in a word document - ready to dazzle and confuse the kiddos.
Dan • 09/29/03 • 12:47 AM:if i were able to add properly i would have gotten the answer, not an hour later. so much for me fixing my careless mistakes habit.
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