Calculating Eccentricity for an Elliptical Orbit

[superaznnerd]

Homework Statement

a satellite is set to orbit a planet of mass 4X 10^20 kg .
It is placed at a distance of separation of 10^7m with a velocity of 30 degrees to the line connecting the center of the planet and the satellite. What will be its eccentrity fo orbit? (Answer is .89)

Homework Equations

ME = KE + PE
KE = 1/2 mv^2
PE = -GMm/r

The Attempt at a Solution

I did 40m/s *sin (30) = vertical velocity.
Then, I plugged it into the equation -GMm/r = .5m(40m/s *sin (30))^2 + -GMm/r

I didn't get the answer though...
please help!

 

[superaznnerd]

help please

 

[Filip Larsen]

You may want to think (or read in your textbook) about how eccentricity (e) is related to the semi-major axis (a) and semi-latus rectum (p), and how those two again are related to the information you were given in the problem text.