Clock Work
When Sylar opened a clock to service, he saw that the big wheel has 21 teeth and the small one 7 teeth. He immediately knew how many times it takes for small wheel to rotate to circle around the big wheel. Do you ?
* Can you believe there is a standard formula for this !
* Can you believe there is a standard formula for this !
Labels: logic, mathemagic
posted by Rajesh Lal at
3:59 AM
20 Comments:
I guess it is possible, there are formulas for loads of things these days.
Yeah!...first post.
I to hot to do this kind of work!
Balerina Angelina + Fardin Forever!
opps why did i post this! i have to ewease it no!!!!!!!!!!! don't press post! no!!!...kgjhk........
How about 6?
Nubmer of teeth on big wheel divided by the number of teeth on small wheel multiplied by 2
(BWT/SWT) * 2
3
i'd go with 3
If you know then Sylar will slice your head open...
well 21/7 3 times so its...
3
I'd say 4.
If the big wheel was a flat surface the small wheel would rotate 3 times to engage 21 teeth. However because the big wheel is itself a circle the small wheel has to complete another revolution to get around it.
So I guess the formula would be Big / Small + 1
The radius of a circle is 2 pi r.
21*3.14 =67.94
7*3.14=20.98
67.94/20.98= 3.46
The answer is 4
21/3 +1
By my estimations its some where in between 3 and 4, so most people have been pretty correct so far.
I'm not much into clocks but the question seems to assume that the small wheel travels around the big one. Is that how they work? I thought all wheels (cog wheels) would have to be fixed to provide gearing ratios.
How do I get to meet hot Angelina?
3 times (21/7=3)
There is no +1 multiplier on this one. And pi (3.1416) does not matter either. These are finite teeth (assuming that the teeth match), there are 21 teeth around the big one, and each time the small one rotates it has covered 7 of those teeth.
Hence 21/7 = 3
Gear Ratios
When two gears are in mesh, the number of teeth in one gear
divided by the number of teeth in the other is called the gear ratio.
Teeth #1 รท Teeth #2 = Gear Ratio
so 21/7=3, so it takes 3 times for the small wheel to rotate around the big wheel
well late to think 4 a right answer coz the last two guys make a good one together...
And for Dicko and others, the radius from those weels can't be measured in teeth coz that is the lengh of the circle...and r from the small well i think that is diffrent than 1/3 from the big one.
Somebody can confirm me that?
this is easy.
Since the small one has 7 teeth and the big one has 21 teeth, if you put a red mark on the two teeth that are in contact right now, then the next time that the red marked two teeth are going to be in contact is in the least commom multiple of 7 and 21 teeths later.
the least commom multiple of 7 and 21 is 21 and since 21 = 21, the next time the red marked teeth come in contact, the big wheel turns exactly 1 time and the small one turns 21/7 = 3 times.
So it takes 3 turns of the small wheel to turn 1 turn of the big wheel
OK, so what's the correct answer?
ANSWER
---------------------
The answer is 4
21/3 +1
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