weight vs. elevation

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mtcastle1

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May 23, 2010
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Problem: Many people know that the weight of an object varies on different planets, but did you know that the weight of an object on Earth also varies according to the elevation of the object? In particular, the weight of an object follows this equation: w=Cr^-2, where C is a constant, and r is the distance that the object is from the center of Earth. Solve the equation w=Cr^-2 for r.
I answer: r^-2=w/C
then, 1/r^2=w/C, r^2=C/w, r=?C/w
Then it goes on to ask: Suppose that an object is 100 lbs. when it is at sea level (3,963 from the center of Earth)
I try this: 3963^-2?c/w = C/100=3963^-2, C=100*3963^2, C=62.952

My question is: am I even close to doing the formula correctly? Because I cannot find anything in the chapter we are working on that relates to elevation vs. weight
 
mtcastle1 said:
Problem: Many people know that the weight of an object varies on different planets, but did you know that the weight of an object on Earth also varies according to the elevation of the object? In particular, the weight of an object follows this equation: w=Cr^-2, where C is a constant, and r is the distance that the object is from the center of Earth. Solve the equation w=Cr^-2 for r.
I answer: r^-2=w/C
then, 1/r^2=w/C, r^2=C/w, r=?C/w
Then it goes on to ask: Suppose that an object is 100 lbs. when it is at sea level (3,963 (units?? ft? mi? km?) from the center of Earth) ---- where is the question? what did they ask for??
I try this: 3963^-2?c/w = C/100=3963^-2, C=100*3963^2, C=62.952

My question is: am I even close to doing the formula correctly? Because I cannot find anything in the chapter we are working on that relates to elevation vs. weight
Click to expand...

You need to read your post - correct it and ask your question.
 
They are asking: "Suppose that an object is 100pounds when it is at sea level. Find the value of C that makes the equation true. (Sea level is 3,963 miles from the center of the Earth.)"
 
Isn't that the square root of your answer? This stuff is Greek to me. Not hung over just ignorant when it comes to Algebra. In fact, I think I'm unteachable when it comes to this stuff.
 
4^2 means 4 to the power 2 = 4 times 4 = 16

sqrt(4) = 2 since 2 times 2 = 4

Are you attending math classes?
 
Online classes, either way I don't understand. A person either has a brain for algebra or they don't. Algebra is "fluid" there doesn't seem to be a constant anything. Suppose this and imagine that. When I am reading a chapter in algebra and it says "imagine the numbers a+b=c" I say that's the alphabet.
Okay, back to your answer, and thank you by the way. When I multiply 3963 *3963 (3963^2) my calculator says 15,705,369. How did you come up with the zero's at the end?
 
mtcastle1 said:
When I multiply 3963 *3963 (3963^2) my calculator says 15,705,369. How did you come up with the zero's at the end?
Click to expand...
BECAUSE there is ALSO a multiplication by 100 involved ; you sure you're not hungover?

If you're as helpless as you say you are, then how in heck did you get this CORRECT:
> I answer: r^-2=w/C
> then, 1/r^2=w/C, r^2=C/w, r=?C/w
 
So, now, "The equation D=1.2(sqrt)h gives distance, D, in miles that a person can see to the horizon from a height, h, in feet. Solve this equation for h."
I say: D=1.2?h D = ?h=D/1.2 = h=[D/1.2]^2 Naturally, I'm guessing because none of it makes any sense.
They go on to ask: "Long's Peak in Rocky Mountain National Park, is 14,255 feet in elevation. How far can you see to the horizon form the top of Long's Peak?"
I say: D=1.2?14,255
D=(1.2)(119.394)
D= 143.27 miles

My question is do I have any idea of what I am doing?
 
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