JEE Mains · Physics · STD 11 - Gravitation
- JEE Mains 2023
- Medium
- MCQ
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 :
Pick an option to check your answer.
Answer & Solution
Correct Answer
(B) \(\sqrt{g R}\)
Step-by-step Solution
Detailed explanation
Loss in \(PE =\) Gain in \(KE\)
\(\left(-\frac{ GMm }{2 R }\right)-\left(-\frac{ GMm }{ R }\right)=\frac{1}{2} mv ^2\)
\(\Rightarrow v ^2=\frac{ GM }{ R }= gR\)
\(\Rightarrow v =\sqrt{ gR }\)
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