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JEE Main 2022 (25 Jul, Shift 2) · Acceleration Due to Gravity

Acceleration Due to Gravity question from JEE Main 2022 (25 Jul, Shift 2)

Q79JEE Main 2022 · 25 JUL · SHIFT 2Medium

Acceleration Due to Gravity

The length of a seconds pendulum at a height h = 2R from earth surface will be: (Given R = Radius of earth and acceleration due to gravity at the surface of earth, g = π\pi2 ms−2{}^{-2})

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Answer: (d)

  1. At h=2Rh = 2R: g′=g(R3R)2=g9=π29g' = g\left(\frac{R}{3R}\right)^2 = \frac{g}{9} = \frac{\pi^2}{9}
  2. Seconds pendulum has T=2T = 2 s, so L=g′T24π2L = \frac{g'T^2}{4\pi^2}
  3. L=(π2/9)(4)4π2=19L = \frac{(\pi^2/9)(4)}{4\pi^2} = \frac{1}{9} m
  4. So the answer is (d) 19\frac{1}{9} m.
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