At the maximum height the particles position has been shown as [tex]\frac{R}{3}[/tex].
The given parameters;
The velocity of the particle is given as;
[tex]v^2 = \frac{GM}{2R}[/tex]
The total mechanical energy of the particle is given as;
[tex]-\frac{GMm}{R} + \frac{1}{2} mv^2 = - \frac{GMm}{R} + \frac{1}{2} mv^2[/tex]
At maximum height the final velocity of the particle is zero.
[tex]-\frac{GMm}{R} + \frac{1}{2} mv^2 = - \frac{GMm}{R +h}[/tex]
[tex]-\frac{GMm}{R} + \frac{1}{2} m\times \frac{GM}{2R} = - \frac{GMm}{R +h}\\\\-\frac{GMm}{R} + \frac{GMm}{4R} = - \frac{GMm}{R +h}\\\\- \frac{3GMm}{4R} = - \frac{GMm}{R +h}\\\\- \frac{3}{4R} = - \frac{1}{R+ h} \\\\3(R+ h) = 4R\\\\3R + 3h = 4R\\\\3h = 4R - 3R\\\\3h = R\\\\h = \frac{R}{3}[/tex]
Thus, at the maximum height the particles position has been shown as [tex]\frac{R}{3}[/tex].
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