Planet is 2.00 a.u. when closest to sun. eccentricty is .500. find period

  • Thread starter c-murda
  • Start date
  • #1
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Homework Statement



a planet is 2.00 a.u. when it is closest to the sun. its eccentricity is .5000. Find its period in years.

Homework Equations





The Attempt at a Solution



i got this so far... don't know if it is right

PD + AD = A
-AD - PD = F <SUBTRACTING THESE TWO>

2PD = A - F
2PD = A - (EA)
2PD = A(1-E)
2PD/(1-E) = A

A = 2(2)/(1.-.5)
A= 8 a.u.

then for a

a= 8.00/2
a= 4.00 a.u.

T^2 = a^3

T = sqrt(a^3)
T = 8

im lost T = 8 what? years?
 

Answers and Replies

  • #2
67
0
kepler's 3rd law says Period( in years) is directly proportional to semi axis (a) cubed. correct?

so was that last line:

T^2 = a^3

correct?
 
  • #3
67
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anyone i got a 7 15 dead line
 

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