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: Physics 250 Problem: Help

  1. Nov 16, 2005 #1
    PROBLEM
    If the size of a new Kuiper object is 0.0150 arc sec in angular size as seen from a distance of 42.00 AU, what is the true diameter? If it has a satellite with a period of 5.50 hours at a semimajor axis of 12500.0 km, what is the mass? What is the resulting density? What do you it is composed of?

    What I know:
    I know that I use V=4/3(pi)r^3 to get the density and previous equations to solve for mass. I don't know how I am supposed to apply the 0.0150 arc seconds or distance to solve for the diameter. What is the equation for that?
     
  2. jcsd
  3. Nov 16, 2005 #2

    Astronuc

    User Avatar
    Staff Emeritus
    Science Advisor

    What is the relationship of the some length of segment on the circumference of a circle and the angle subtended by that segment?
     
  4. Nov 16, 2005 #3
    I have no idea what you mean when you say "angle subtended..."
     
  5. Nov 16, 2005 #4
    Is the concept of angular size the trouble here. Here is a diagram, with this you should know what to do...
    http://www.berrys.plus.com/hh5.gif [Broken]

    So the furthur away the object is, the smaller the angular size will become.

    Hope this helps...
    Sam
     
    Last edited by a moderator: May 2, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook