Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Gravitational Near Earth Surface.

  1. Mar 16, 2010 #1
    1. The problem statement, all variables and given/known data

    Certain neutron stars (extremely dense stars) are believed to be rotating at about 1000 rev/s. If such a star has a radius of 7 km, what must be its minimum mass so that material on its surface remains in place during the rapid rotation?

    2. Relevant equations

    cramster-equation-201031601226340429448270400007570.gif



    3. The attempt at a solution

    (7x10^3)(1000*2pi)/6.67*10^-11= 2.0301495

    I'm getting it wrong. Any hints why?
     
  2. jcsd
  3. Mar 16, 2010 #2

    ehild

    User Avatar
    Homework Helper

    You forgot to cube the value of R.

    ehild
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook