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Weight and Radius

  • Thread starter susan__t
  • Start date
20
0
1. Homework Statement
Pat's mass is 65.5 kg on Earth's surface. What would Pat's weight be at an altitude twice the radius of the Earth


2. Homework Equations
Fg=G(m1)(m2)/r^2
G = 6.67X 10^-11
F=ma

We are not given the numerical radius of the Earth

3. The Attempt at a Solution
I tried to manipulate the formula a bit:
(using the gravitational law)
Fg = (65.5)x/ 2^2

And that got me nowhere.
I also know the answer is 71.4N but how you get there is what I don't understand.
 

Answers and Replies

hage567
Homework Helper
1,509
1
Fg=G(m1)(m2)/r^2
This equation should work. What are you using for each variable? Look up data you need. It's probably in your textbook somewhere.
 
Nabeshin
Science Advisor
2,204
16
While hage's solution is valid, I think we know g=9.8 for the surface of the Earth. Therefore, you can look at the equation and see how this force would change as R increases. Think about what is constant and what is changing.
 

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