Physics - Gravitation Question with Solution | TestHub

PhysicsGravitationField & ForceEasy2 minPYQ_2020
PhysicsEasysingle choice

In older times, people used to think that the Earth was flat. Imagine that the Earth is indeed not a sphere of radiusR, but an infinite plate of thicknessH. What value ofHis needed to allow the same gravitational acceleration to be experienced as on the surface of the actual Earth? (Assume that the Earth's density is uniform and equal in the two models).

Options:

Answer:
A
Solution:



Applying Gauss law

E.ds=4πGmin

Where E is gravitational field atds

Computing over colsed surface given

E2s=4πG(ρsh)

E= 4πG ρh 2 ... (1)

On the surface of earth with radiusR, E= G( ρ 4 3 π R 3 ) R 2

=Gρ 4 3 πR ... (2)

Equating (1) and (2)

4π Gρh 2 =Gρ 4 3 πR

h= 2R 3

Subject:PhysicsTopic:GravitationSubtopic:Field & Force
2mℹ️ Source: PYQ_2020

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