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Homework Help: Acceleration due to gravity problem.Help!

  1. May 15, 2008 #1
    1. The problem statement, all variables and given/known data
    "Determine the acceleration due to gravity on the planet Mercury which has a mass of 3.30*10^23kg and a diameter of 4878 km.

    2. Relevant equations
    Mp is mass of planet
    Rp is radius of planet

    3. The attempt at a solution
    First off I needed to change the diameter into the radius. In my class I have to convert km to m.

    4878 km*1000= 4,878,000 m

    4,878,000/2= 2,439,000

    2,439,000 is the radius

    Next, plugged in.


    (6.67*10^-11)(3.30*10^23)/2,439,000^2 = 3.70 g on Mercury.

    I'm pretty sure this is correct just want to make sure. Thanks for looking it over!
  2. jcsd
  3. May 15, 2008 #2


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    Welcome to PF!

    Hi NewtonJR! Welcome to PF! :smile:

    That's a very well-laid out solution … I can see exactly what you're doing!

    Yes, that's fine … except I think you don't mean that "g" at the end, do you? :smile:

    btw, as a check (which is often useful to make sure we're not 1000 out!), if we assume that Mercury's density is roughly the same as the Earth's, then mass is proportional to r³, so surface gravity is proportional to r, so should be about 40% of g, = about 4. Yippee! :biggrin:
  4. May 15, 2008 #3
    Thanks for the welcome! Thanks for the feedback also. No, I didn't mean to put that "g" at the end.:cool:
  5. May 15, 2008 #4
    This problem is SOLVED.
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