help with a math problem...

jimkonow · 03-14-2008, 01:39 PM

well guys, i hate math. i have no idea how to go about doing this problem, and i need your help, because youre smart.
here it goes:
suppose there was a steel band fitting tightly around the equator of the earth. now suppose you remove it and cut it at one place, and then add an additional piece which is 20 feet long. if each point of the band is an equal distance from the equator, how far off the equator will it be?

the only hint my teacher gave me is that C=2(pi)r

helppppp!

Jet · 03-14-2008, 02:17 PM

Circumference = 2(pi)radius

Quote:

What is the diameter of the earth?
The diameter of the earth at the equator is 7,926.41 miles

Thus, the radius is 3963.205 miles.

Also, 20 feet equals 0.0037878787 miles

2(pi)3963.205 miles +0.0037878787 miles = 24901.55521

24901.55521 = 2(pi)(newradius)

3963.205603 = new radius

Distance from the earth = new radius - earth's radius = 3963.205 miles - 3963.205603 miles = 0.0006028597 miles

0.0006028597 miles * 5280 = 3.183099216 feet

newguy5 · 03-14-2008, 02:18 PM

first of all you need to know a couple of things. 2(pi)r is 2 times pi times the radius of the earth, which gives you the circumfrence of the earth but also in this equation gives you the initial length of the steel band (since it fits around the earth perfectly). now, since the band is going to be altered in FEET, we need to convert the earth's circumfrence into feet, not miles.

the earth's radius is about 3950 miles. that is roughly 3950 x 5280 (feet in a mile) = 20,856,000 feet.

in the equation, 2(pi)r, we have 2*3.14*20856000 = 130,975,680 feet. so the circumfrence of the earth is that many feet and so is the length of the band.

now increasing the band by 20 feet makes the band now 130,975,700 feet, and we just flip the original equation around to find out the new radius the earth would have to be to adjust to our 20 foot extension.

so basically we have from C = 2(pi)r, C/2(pi) = r, or 130,975,700/(2*3.14) = 20,856,003.18. so that means the radius is now off by 3.18 feet, which also means that at any point the radius is off by 3.18 feet, which means that by adding 20 feet to the extension of your steel band, you make the band 3.18 feet away from the equator at any point.

or at least i think that's the right answer.

Jet · 03-14-2008, 02:21 PM

It is.

newguy5 · 03-14-2008, 02:33 PM

Quote:

Originally Posted by Jet

It is.

i used to hate math until i took advanced calculus in college, and then i hated advanced calculus but thought math was okay!

**Cromewell** · 03-14-2008, 09:18 PM

Calculus is easy though. You only need 1 formula

jimkonow · 03-15-2008, 03:11 PM

thanks guys

03-14-2008, 01:39 PM	#1 (permalink)
jimkonow Platinum Member Join Date: Jan 2007 Location: Chatham, New York Age: 17 Posts: 939	help with a math problem... well guys, i hate math. i have no idea how to go about doing this problem, and i need your help, because youre smart. here it goes: suppose there was a steel band fitting tightly around the equator of the earth. now suppose you remove it and cut it at one place, and then add an additional piece which is 20 feet long. if each point of the band is an equal distance from the equator, how far off the equator will it be? the only hint my teacher gave me is that C=2(pi)r helppppp! __________________ E4500 @ 2.2GHz Acer AL2216W @ 1680x1050 Gigabyte P35-DS3L 2048MB OCZ DDR2-800 80GB Excelstor SATA 3.0 MSI HD2600XT (256MB GDDR4) NEC DVD-R-DL

03-14-2008, 02:18 PM	#3 (permalink)
newguy5 Diamond Member Join Date: Jan 2007 Location: Dallas, Tx Age: 25 Posts: 1,076	first of all you need to know a couple of things. 2(pi)r is 2 times pi times the radius of the earth, which gives you the circumfrence of the earth but also in this equation gives you the initial length of the steel band (since it fits around the earth perfectly). now, since the band is going to be altered in FEET, we need to convert the earth's circumfrence into feet, not miles. the earth's radius is about 3950 miles. that is roughly 3950 x 5280 (feet in a mile) = 20,856,000 feet. in the equation, 2(pi)r, we have 23.1420856000 = 130,975,680 feet. so the circumfrence of the earth is that many feet and so is the length of the band. now increasing the band by 20 feet makes the band now 130,975,700 feet, and we just flip the original equation around to find out the new radius the earth would have to be to adjust to our 20 foot extension. so basically we have from C = 2(pi)r, C/2(pi) = r, or 130,975,700/(2*3.14) = 20,856,003.18. so that means the radius is now off by 3.18 feet, which also means that at any point the radius is off by 3.18 feet, which means that by adding 20 feet to the extension of your steel band, you make the band 3.18 feet away from the equator at any point. or at least i think that's the right answer. __________________ C2D E6750 Arctic Freezer 7 Pro 2GB G.Skill RAM PC2-6400 Gigabyte P35-DS3L Sapphire Radeon 3850 250GB Seagate Barracuda 7200.10 Thermaltake TR2 500W 22" Westinghouse (widescreen)

03-14-2008, 02:21 PM	#4 (permalink)
Jet Diamond Member Join Date: Oct 2005 Posts: 5,286	It is. __________________ Macbook/Intel Core Duo 1.83Ghz/2GB DDR2 667/60GB HD/OSX 10.4.11/160GB 3.5" Firewire External/160GB Maxtor One Touch 4 Mini External/

03-14-2008, 09:18 PM	#6 (permalink)
Cromewell Moderator Join Date: Dec 2004 Location: Canada Age: 25 Posts: 10,117	Calculus is easy though. You only need 1 formula __________________ You know what the chain of command is? It's the chain I go get and beat you with 'til ya understand who's in ruttin' command here. I must plug a couple comics because they are good :D: www.ctrlaltdel-online.com www.userfriendly.org

03-15-2008, 03:11 PM	#7 (permalink)
jimkonow Platinum Member Join Date: Jan 2007 Location: Chatham, New York Age: 17 Posts: 939	thanks guys __________________ E4500 @ 2.2GHz Acer AL2216W @ 1680x1050 Gigabyte P35-DS3L 2048MB OCZ DDR2-800 80GB Excelstor SATA 3.0 MSI HD2600XT (256MB GDDR4) NEC DVD-R-DL

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