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Gravitation question

2023 · 10 Apr · Shift 2 · Q54
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  5. /2023 · 10 Apr · Shift 2 · Q54

Gravitation question

2023 · 10 Apr · Shift 2 · Q54

JEE MainPhysicsGravitationMCQ+4 / −1
Given below are two statements: Statement I : Rotation of the earth shows effect on the value of acceleration due to gravity (g) Statement II : The effect of rotation of the earth on the value of 'g' at the equator is minimum and that at the pole is maximum. In the light of the above statements, choose the correct answer from the options given below
  1. A
    Statement I is false but statement II is true
  2. B
    Statement I is true but statement II is false
  3. C
    Both Statement I and Statement II are true
  4. D
    Both Statement I and Statement II are false
View written solutionFree

Correct answer: B

  1. Effect of Earth's rotation on ggg

Because the Earth rotates, a body on its surface experiences a centrifugal effect.

At latitude λ\lambdaλ, the effective acceleration due to gravity is reduced by the component of centrifugal acceleration:

geff=g−ω2Rcos⁡2λg_{\text{eff}} = g - \omega^2 R \cos^2 \lambdageff​=g−ω2Rcos2λ

where:

  • ω\omegaω = angular speed of Earth,
  • RRR = radius of Earth,
  • λ\lambdaλ = latitude.

So, the rotation of the Earth does affect the value of acceleration due to gravity.

Hence, Statement I is true.


  1. Where is the effect maximum and minimum?

From

Δg=ω2Rcos⁡2λ\Delta g = \omega^2 R \cos^2 \lambdaΔg=ω2Rcos2λ

the reduction in ggg due to rotation depends on cos⁡2λ\cos^2 \lambdacos2λ.

  • At the equator: λ=0∘\lambda = 0^\circλ=0∘

cos⁡20∘=1\cos^2 0^\circ = 1cos20∘=1

So the reduction is maximum.

  • At the pole: λ=90∘\lambda = 90^\circλ=90∘

cos⁡290∘=0\cos^2 90^\circ = 0cos290∘=0

So the reduction is minimum (zero).

Therefore, Statement II says the opposite of the correct fact.

Hence, Statement II is false.


  1. Evaluate the options
  • A: Statement I false, Statement II true →\to→ incorrect
  • B: Statement I true, Statement II false →\to→ correct
  • C: Both true →\to→ incorrect
  • D: Both false →\to→ incorrect

  1. Final answer

The correct option is:

B\boxed{\text{B}}B​

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