JEE Advanced · Physics · 9. Gravitation
A planet of radius (radius of Earth) has the same mass density as Earth. Scientists dig a well of depth on it and lower a wire of the same length and of linear mass density into it. If the wire is not touching anywhere, the force applied at the top of the wire by a person holding it in place is (take the radius of Earth and the acceleration due to gravity of Earth is )
- A 96 N
- B 108 N
- C 120 N
- D 150 N
Answer & Solution
Correct Answer
(B) 108 N
Step-by-step Solution
Detailed explanation
Inside planet
Force to keep the wire at rest (F)
= weight of wire
Here, density of earth
Also, ; putting all values,
Force to keep the wire at rest (F)
= weight of wire
Here, density of earth
Also, ; putting all values,
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