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: Astronaut weight

  1. Jun 2, 2010 #1
    An astronaut weighs 1000N at the surface of the earth of radius 6500 km, what his weight will be at 13000 km and 19500km from the centre of the earth?

    Do I have to calculate the new value of g at 13000 km using the following?

    (G• Mearth) / (Rearth)2
    G = 6.673 x 10-11 N m2/kg2
    Mass of the earth = (5.98 x 1024 kg)

    New Re = 13000 km (converted to m)

    Then W = M x g

    Is there another way of solving it?
  2. jcsd
  3. Jun 2, 2010 #2

    Filip Larsen

    User Avatar
    Gold Member

    You can calculate the answer without knowing the values G and M (or GM). Try write up the equation for the weight W1 at radius R1 and the weight W2 at radius R2 using GM as you did above and then look at the ratio W1/W2.
  4. Jun 4, 2010 #3
    Great answer Filip, thanks
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook