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Gravitational Acceleration-Orbital Motion

  • Thread starter physgrl
  • Start date
  • #1
138
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Homework Statement



The weight of a 0.60 kg object at the surface of Planet V is 20 N. The radius of the planet is 4 x 10^6 m. Find the gravitational acceleration at a distance of 2 x 10^6 m from the surface of this planet.

a. 8.9 m/s2
b. 11 m/s2
c. 13 m/s2
d. 18 m/s2


Homework Equations



F=ma
a=MG/r^2


The Attempt at a Solution



I did
acceleration at surface=20N/.6kg=33.33m/s^2
acceleration at surface=MG/r^2
MG=33.33m/s^2*(4x10^6)^2

acceleration at a distance=MG/(r+d)^2
a at a distance=(33.33m/s^2*(4x10^6)^2)/(2x10^6+4x10^6)^2
a=14.8m/s^2 which is not in the options
 

Answers and Replies

  • #2
1,506
17
I can't see anything wrong with your method. I did exactly the same and got the same answer as you !!!!
It will be interesting to see if there are any other responses to your posting.
 
  • #3
phyzguy
Science Advisor
4,394
1,369
I think you did it right and the question is wrong. Anyone else see an error?
 
  • #4
798
1
I get 8.89...
 
  • #5
1,506
17
The weight will be 8.89N
 
  • #6
798
1
Settled! Answers wrong
 
  • #7
phyzguy
Science Advisor
4,394
1,369
It doesn't ask for the weight, it asks for the acceleration, which should be 14.8 like the OP calculated.
 
  • #8
138
0
thanks :D
 

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