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Circular Motion and Universal Law of Gravitation Solutions Check Requested!

  • Thread starter rain_ex
  • Start date
  • #1
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Homework Statement



1. A typical white dwarf star, which once was an average star like our Sun but now in the last stage of its evolution, is the size of our Moon but has the mass of our Sun. What is the surface acceleration due to gravity on this star? (Msun = 1.99 x 10^30 kg, Rmoon = 1.74 x 10^6 m)

- R = radius and M = mass (in reference to Msun and Rmoon)

Homework Equations



Universal Law of Gravitation
0f36df929ac9d711a8ba8c5658c3bfee.png


The Attempt at a Solution



I don't know how to start, but still gave it a try.
First of all, I didn't know what the "F" on the other side of the equation is supposed to be or set the equation up to find the acceleration.
I started by substituting G for 6.67426x10^-11 and got rid of the 2nd mass altogether.
I plugged in the mass of the sun, 1.99x10^30 kg divided by the radius of the moon, 1.74x10^6 m.
Thus I ended up with 4.38x10^7 m/s^2.

Is this the solution?
 

Answers and Replies

  • #2
verty
Homework Helper
2,164
198
Your try was a good one, well figured out.

We have [tex]F = m_2 a = G \frac{m_1 m_2}{r^2},[/tex]
so [tex]a = G \frac{m_1}{r^2}.[/tex]
 

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