SOLUTION: Here is a two part question: Did you know that the weight of an object on earth also varies according to the eleveation of the object? In particular, the weight of an object fo

Algebra ->  Radicals -> SOLUTION: Here is a two part question: Did you know that the weight of an object on earth also varies according to the eleveation of the object? In particular, the weight of an object fo      Log On


   

Question 175492: Here is a two part question:
Did you know that the weight of an object on earth also varies according to the eleveation 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 the earth.
a. Solve the equation w=Cr^-2 for r.
b. Suppose that the 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.)
I have no idea how to start with part a. PLease help.

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
I'll help you with part a) (which will hopefully make you understand part b). If not, then feel free to ask further.


a)

w=Cr%5E%28-2%29 Start with the given equation.


w=C%281%2Fr%5E2%29 Rewrite r%5E%28-2%29 as 1%2Fr%5E2


w=C%2Fr%5E2 Multiply.


wr%5E2=C Multiply both sides by r%5E2


r%5E2=C%2Fw Divide both sides by "w".


r=sqrt%28C%2Fw%29 Take the square root of both sides. Note: since "r" is the distance, this means that we're only considering the positive square root.


So the answer is r=sqrt%28C%2Fw%29