What is the Maximum Height Attained by an Object Launched from Earth's Surface?

AI Thread Summary
An object launched vertically from Earth's surface with an initial speed less than escape velocity reaches a maximum height determined by the equation h = (R_E * v_i^2) / (v_esc^2 - v_i^2). The discussion includes a derivation of energy conservation principles, equating kinetic and gravitational potential energy at different heights. A participant expresses confusion about a specific step in the derivation, particularly the transition to an equation relating initial and escape velocities. The conversation highlights the importance of understanding energy conservation in the context of gravitational forces. Clarification on the derivation step is sought to enhance comprehension of the underlying physics.
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Homework Statement


An Object is fired vertically upward from the surface of the Earth ( of radius RE ) with an initial speed vi that is comparable to but less than the escape speed vesc

Show that the object attains a maximum height h given by h=\stackrel{R_{E}v^{2}_{i}}{v^{2}_{esc}-v^{2}_{i}}

Homework Equations


The Attempt at a Solution


I have the solution but I am confused with a step.
Here is the solution provided up until the step on which I am confused:

(K+U_{g})_{f}=(K+U_{g})_{f}

\stackrel{1}{2}mv^{2}_{i} - \stackrel{GmM_{E}}{R_{E}} = 0 - \stackrel{GmM_{E}}{R_{E}+h}

where \stackrel{1}{2}mv^{2}_{esc}= \stackrel{GmM_{E}}{R_{E}}

Then\stackrel{1}{2}v^{2}_{i} - \stackrel{1}{2}v^{2}_{esc}= -\stackrel{1}{2}v^{2}_{esc} (\stackrel{R_{E}}{R_{E}+h})

So the jump I am confused about is the equation that follows the "Then" Statement. I'm not sure why this is true.

(sorry for the poor look of the equations. Hopefully its readable, I wasn't sure how to make fractions.)
 
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