Homework Help Forum: physics

Posted by Sasha on Monday, October 26, 2009 at 10:03pm.

calculate the force of Earth's gravity on a spacecraft 12,800 km (2 Earth radii) above Earth's surface if its mass is 1350 kg. i know the universal gravitation formula is Fg = G [(m1 m2)/ r^2] but im not getting anywhere near the multiply choice answers of: 14,470, 4410 N, 2205 N, or 1470 N

• physics - MathMate, Monday, October 26, 2009 at 10:16pm

  r is the distance to the centre of the body. What did you use for r?

  
  

• physics - Sasha, Monday, October 26, 2009 at 10:26pm

  i tried squaring earth's radii and i tried multiplying it by 2

  
  

• physics - MathMate, Monday, October 26, 2009 at 10:46pm

  Ouch! "(2 Earth radii) above Earth's surface" means 3 earth radii from the centre, right?

  
  

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