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re: Math Riddle: How much string would you add....
Posted on 7/25/14 at 6:36 pm to tigerpawl
Posted on 7/25/14 at 6:36 pm to tigerpawl
quote:
Who started the rumor that Chickens have small brains?
Whoa, whoa, whoa. Hold on one damned minute.
When you're using the vast reservoir of mental prowess that is the OT as a point of comparison, even a small chicken brain looks behemoth.
The OT: Where even the chickens look smart.
This post was edited on 7/25/14 at 6:40 pm
0
Posted on 7/25/14 at 6:47 pm to Spock's Eyebrow
If the string is elastic, then zero....just stretch. 
Posted on 7/25/14 at 7:05 pm to tigerpawl
Surprisingly simple:
The circumference of a circle = 2pi * r (radius)
Therefore, adding 1 foot to the circumference means this is now 2pi * (r+1) = (2pi*r) + 2pi
The extra amount of string required is therefore 2pi times the additional height, in this case 2pi feet.
The circumference of a circle = 2pi * r (radius)
Therefore, adding 1 foot to the circumference means this is now 2pi * (r+1) = (2pi*r) + 2pi
The extra amount of string required is therefore 2pi times the additional height, in this case 2pi feet.
Posted on 7/25/14 at 7:15 pm to foshizzle
quote:And for you Alabama fans...
The extra amount of string required is therefore 2pi times the additional height, in this case 2pi feet.
This post was edited on 7/25/14 at 7:17 pm
Posted on 7/25/14 at 7:44 pm to tigerpawl
They way I see it, you need to find the radius first.
25,000= pi*2*r
Or
12,500=pi*r
Or
r= 3,980.81
Thend find new circumference by adding new radius, whice would be 1ft extra.
2 * pi * 3981.81= c
Or
6.28*3981.81
C= 25,005.7
My answer is 6 whole feet.
What am i missing?
25,000= pi*2*r
Or
12,500=pi*r
Or
r= 3,980.81
Thend find new circumference by adding new radius, whice would be 1ft extra.
2 * pi * 3981.81= c
Or
6.28*3981.81
C= 25,005.7
My answer is 6 whole feet.
What am i missing?
Posted on 7/25/14 at 7:56 pm to Cmlsu5618
quote:
My answer is 6 whole feet.
What am i missing?
For starters, you're using a not very good approximation for pi in 3.14. Second, you're plugging in a bunch of numbers which misses the whole point. See foshizzle's post for a correct derivation that reveals the surprising fact that the answer is independent of the size of the sphere; that is, it's the same for a marble, a basketball, the Earth, the Sun, etc.
Posted on 7/25/14 at 8:04 pm to tigerpawl
1. 2pi x r = C
2. 2pi x (r + 1ft) = C'
3. (2pi x r) + (2pi x 1ft) = C'
4. C + 2pi = C'
5. C' - C = 2pi
Assume all units are in feet...
2. 2pi x (r + 1ft) = C'
3. (2pi x r) + (2pi x 1ft) = C'
4. C + 2pi = C'
5. C' - C = 2pi
Assume all units are in feet...
This post was edited on 7/25/14 at 8:12 pm
Posted on 7/25/14 at 8:18 pm to tigerpawl
The square root of 25001 squared minus 25000 squared....or some stupid shite like that.
Posted on 7/25/14 at 8:18 pm to Spock's Eyebrow
There are some things that I just can't get, I believe it, and it is starting to make sense but dammit I feel dumb 
Posted on 7/25/14 at 8:21 pm to tigerpawl
quote:
quote: Approximately 25,004' ? refer to the OP link for the "cryptic answer"... How much new string would you add to the original 25,000 mile string?
Gotcha! I forgot about subtracting the circumference.
Posted on 7/25/14 at 8:23 pm to tigerpawl
This is really easy.
Posted on 7/25/14 at 8:25 pm to Zyggy
Your math is wonky.
Posted on 7/25/14 at 8:28 pm to foshizzle
quote:
foshizzle
quote:That's how I figured it out. Sub "circumference" with "radius" #physicsbrain
Therefore, adding 1 foot to the circumference means this is now 2pi * (r+1) = (2pi*r) + 2pi
This post was edited on 7/25/14 at 8:29 pm
Posted on 7/25/14 at 8:33 pm to ell_13
Why add the 2 pi at then end?
Posted on 7/25/14 at 8:33 pm to dj30
weren't you the one with that math riddle a guy at an interview asked you? that one was fun.
Posted on 7/25/14 at 8:43 pm to ell_13
quote:
#physicsbrain
My undergrad degree was Physics. The curriculum taught me how to attack these problems quite well. In this case it really doesn't depend on the radius at all.
Posted on 7/25/14 at 8:45 pm to Pectus
quote:It's a distribution. The 2pi added at the end is the difference and gives you the answer to the problem.
Why add the 2 pi at then end?
foshizzle, mine too. I never got a grad degree. Went straight into teaching high school math, then IT for a power generation company.
This post was edited on 7/25/14 at 8:49 pm
Posted on 7/25/14 at 9:30 pm to ell_13
The original string (circumference; 25,000 x 5,280 ft) = 132,000,000 ft
The original diameter = 42,016,904.97626037 ft
The new diameter = 42,016,906.97626037 ft (2 ft longer)
The new circumference = 132,000,006.28318532 ft
Therefore, ergo and hither to...
132,000,006.28318532 ft - 132,000,000 ft = 6.28318532 ft
Diameter/Circumference Calculator
The original diameter = 42,016,904.97626037 ft
The new diameter = 42,016,906.97626037 ft (2 ft longer)
The new circumference = 132,000,006.28318532 ft
Therefore, ergo and hither to...
132,000,006.28318532 ft - 132,000,000 ft = 6.28318532 ft
Diameter/Circumference Calculator
This post was edited on 7/25/14 at 9:41 pm
Posted on 7/25/14 at 9:33 pm to foshizzle
quote:It's an inherent characteristic of all spheres.
In this case it really doesn't depend on the radius at all.
quote:It is if you express everything in terms of feet.
This is really easy.
This post was edited on 7/25/14 at 9:36 pm
Posted on 7/25/14 at 9:41 pm to tigerpawl
quote:
It is if you express everything in terms of feet.
No - the unit of measurement is irrelevant to the solution.
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