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#1 2007-05-26 08:46:51
- lcbuys
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- Registered: 2007-05-26
- Posts: 2
trig world problem
You travel in your trusty car with the 25 inch wheels. You installed a nifty gadget that measures how often your wheels turn each hour.It show that right now they turn 41000 times per hour. You figure you are going at a speed of ________miles per hour.
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#2 2007-05-26 10:52:02
- lcbuys
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- Registered: 2007-05-26
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Re: trig world problem
Thats the wrong answer. How did you try and figure it out?
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#3 2007-05-26 11:13:02
- MathsIsFun
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- Registered: 2005-01-21
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Re: trig world problem
41000 revs/h * (25 π)in/rev / (12 in/ft * 5280 ft/mi) = 50.8 mi/h
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman
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#4 2007-05-26 11:14:45
- mathsyperson
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- Registered: 2005-06-22
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Re: trig world problem
Here's what I get.
The wheels have a diameter of 25 inches, which means that their circumference is 25π inches, or roughly 78.5. So for every revolution of the wheel, the car travels 25π inches (ignoring any possible skidding).
The wheels turned 41000 times, which means that the car travelled ~3220132 inches.
3220132 inches = 268344 feet = 89448 yards = 50.8 miles.
So the car travels at approximately 50.8 miles per hour.
Why did the vector cross the road?
It wanted to be normal.
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