1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Gravity/Circular Motion

  1. Jan 30, 2007 #1
    hey, i am really stuck on this problem and i was wondering if anyone could help me...

    The planet Mercury orbits the Sun at a mean distance of 5.80X10^7 km.
    a) calculate the strength of the Sun's gravity field (g) at Mercury's mean distance.
    b) Calculate Mercury's orbital speed in m/s and in km/h.


    Any assistance on the problem would be greatly appreciated!!
     
  2. jcsd
  3. Jan 30, 2007 #2

    ranger

    User Avatar
    Gold Member

    Hi vasfinest18,

    In the future, post questions like these in the homework section. And lastly, you must show an attempt. So any thoughts what to do?
     
  4. Jan 30, 2007 #3
    is the formula that i need to use g=GM/r^2??? there must be some more info that i need to derive from the problem, because i was only given 1 number. should i substitute 10m/s^2 in for G?? but if that is the right equation to use, i am still missing another piece of info that i would need...
     
  5. Jan 30, 2007 #4
    1. The problem statement, all variables and given/known data
    The planet Mercury orbits the Sun at a mean distance of 5.80X10^7 km.
    a) calculate the strength of the Sun's gravity field (g) at Mercury's mean distance.
    b) Calculate Mercury's orbital speed in m/s and in km/h.


    2. Relevant equations
    g=GM/r^2... i think but i need 3 out of those 4 variables, and i only have 1 given.. G is mostly likely 10 m/s^2, but from there i dont know how to calculate 'g' or M.


    3. The attempt at a solution
     
  6. Jan 30, 2007 #5

    ranger

    User Avatar
    Gold Member

    Well for first problem, you are right track. G is simply the gravitational constant (look up the value). r is the distance between the sun and mercury. And you already know the mass of the sun. Just plug in the values into the formula and all should be good.
     
  7. Jan 30, 2007 #6

    Pyrrhus

    User Avatar
    Homework Helper

    Open your physics book, there you will find the values you don't have. Usually on a table.
     
  8. Jan 30, 2007 #7

    ranger

    User Avatar
    Gold Member

  9. Jan 30, 2007 #8
    is the mean distance the radius? and for the mass should i just look up the mass of the sun?
     
  10. Jan 30, 2007 #9

    ranger

    User Avatar
    Gold Member

    Obviously you must look up the mass if you do not know it.
     
  11. Jan 31, 2007 #10

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    If this thread appears to be confusing, that's because it has been merged with another that was posted in the wrong forum.

    Please do NOT cross post.

    Zz.
     
  12. Aug 22, 2009 #11
    I dont find this thread constructive at all.
    The question is blatantly straightforward.

    g=GM/r²
    where g = gravitational strength at that point,
    G = gravitational constant,
    M = mass of the object "creating" the gravity field, the sun in this case,
    r = distance between the CG(center of gravity) sun and CG of the planet.

    You should read up on any physics textbooks on chapter about gravitation before asking.

    Edit:
    and as for the second part, its another rigid equation you can find under circular motion. zzz
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Gravity/Circular Motion
Loading...