• Support PF! Buy your school textbooks, materials and every day products Here!

Find Pluto's year length using Kepler's third law.

  • Thread starter D.J Falcon
  • Start date
  • #1

Homework Statement



Pluto is 40 times further from the Sun than we are. How long is a year on Pluto? (Use Kepler's third law.)


Homework Equations



4∏^2/Gm=T^2/r^3


The Attempt at a Solution



Te^2(Earth period)=x*r^3

Tp^2(Pluto period)=x*(40r)^3


I don't know what to do exactly from here. I'm not even entirely sure that I'm going about this the right way.

Any help would be appreciated.
 

Answers and Replies

  • #2
241
0
Hint: For every planet [which goes around the sun] in our solar system R^3/T^2=constant.
Why?
 
  • #3
Hint: For every planet [which goes around the sun] in our solar system R^3/T^2=constant.
Why?
I've already made x a constant (T^2/r^3), in the attempt at a solution. I just don't realise what to do from there.
 
  • #4
241
0
I don't know what you mean by:
I've already made x a constant (T^2/r^3), in the attempt at a solution.
...
First of all you need to understand why for every planet which goes around the same star R^3/T^2 is constant.
Then don't forget what you already know about the difference in R between earth and Pluto.

I'm already gave you the answer, actually...
 

Related Threads for: Find Pluto's year length using Kepler's third law.

Replies
2
Views
425
Replies
5
Views
474
  • Last Post
Replies
6
Views
2K
  • Last Post
Replies
5
Views
5K
  • Last Post
Replies
6
Views
2K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
11
Views
2K
  • Last Post
Replies
1
Views
1K
Top