QJEEM23Phc07b: JEE Main 2023 Physics - Class 11 JEEM23Phc07b Solution: An object is allowed to fall from a height above the earth,…

Question

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An object is allowed to fall from a height

R

above the earth, where

R

is the radius of earth. Its velocity when it strikes the earth's surface, ignoring air resistance, will be

Accepted Answer

${U_P} = - {{GMm} \over {2R}}$

${U_S} = - {{GMm} \over R}$

$\Rightarrow$ Energy conservation

${1 \over 2}m{v^2} - {{GMm} \over R} = - {{GMm} \over {2R}}$

${v^2} = {{GM} \over R}$

$v = \sqrt {{{GM} \over R}} = \sqrt {gR}$

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