Posted by **ASD** on Friday, September 17, 2010 at 10:02am.

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.

a.Solve the equation w=Cr^-2 for r. The answer I came up with is r^-2=w/C: is this correct?

And would you please help me with b?

b.Suppose that an object is 100 pounds 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.)

Thank you!

- Math -
**ASD**, Friday, September 17, 2010 at 11:03am
Ok, I went back and tried again. The equation I found when solving for r is r=sqrt(C/w)

Is this correct?

Then in b I would plug in the 100 for w, and the 3,963 for r to find the constant, C, correct?

- Math -
**PsyDAG**, Friday, September 17, 2010 at 11:06am
a is correct.

C = w/r^-2

w = 100

r = 1/(3963)^2

Solve for C.

- Math -
**ASD**, Friday, September 17, 2010 at 11:29am
So would my equation be C=100/(3963)^2 ...I'm confused

- Math -
**ASD**, Friday, September 17, 2010 at 11:57am
Please let me know if I did this correct for b...

100=C/(3,963)^2

100=C/15,705,369

100*C=(C/15,705,369)*C

100C=15,705,369

100C/100=15,705,369/100

C=157,053.69

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