An object is kept at rest at a distance of 3 R above the earth's surface where R is earth's radius. The…

An object is kept at rest at a distance of 3 R above the earth's surface where R is earth's radius. The minimum speed with which it must be projected so that it does not return to earth is :
(Assume $\mathrm{M}=$ mass of earth, $\mathrm{G}=$ Universal gravitational constant)
  1. $\sqrt{\frac{\mathrm{GM}}{2 \mathrm{R}}}$
  2. $\sqrt{\frac{\mathrm{GM}}{\mathrm{R}}}$
  3. $\sqrt{\frac{3 \mathrm{GM}}{\mathrm{R}}}$
  4. $\sqrt{\frac{2 \mathrm{GM}}{\mathrm{R}}}$

Solution


$\begin{aligned}
& \mathrm{P}_{\mathrm{P}}+\mathrm{k}_{\mathrm{P}}=\mathrm{P}_{\mathrm{o}}+\mathrm{k}_0 \\ & -\frac{\mathrm{GMm}}{4 \mathrm{R}}+\frac{1}{2} \mathrm{mV}_{\mathrm{P}}^2=0 \\ & \mathrm{~V}_{\mathrm{P}}=\sqrt{\frac{\mathrm{GM}}{2 \mathrm{R}}}
\end{aligned}$
Choice 1

Asked in: JEE Main 2025 (04 Apr Shift 2)

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