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MHT CET 2026 (14 May, Shift 2) · Errors in Measurement

Errors in Measurement question from MHT CET 2026 (14 May, Shift 2)

Q20MHT CET 2026 · 14 MAY · SHIFT 2Medium

Errors in Measurement

The period of oscillation of a simple pendulum is T=2πlgT = 2\pi\sqrt{\frac{l}{g}} where ll is about 100100 cm and has 11 mm accuracy. The period is about 22 s. The time of 100100 oscillations is measured by a stopwatch of least count 0.10.1 s. The percentage error in 'gg' is (gravitation acceleration)

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Answer: (c)

  1. g=4π2lT2g = \frac{4\pi^2 l}{T^2}, so Δgg=Δll+2ΔTT\frac{\Delta g}{g} = \frac{\Delta l}{l} + 2\frac{\Delta T}{T}
  2. Δll=0.1 cm100 cm=0.1%\frac{\Delta l}{l} = \frac{0.1\text{ cm}}{100\text{ cm}} = 0.1\%
  3. Time of 100 oscillations =200 s= 200\text{ s}, so ΔTT=0.1200=0.05%\frac{\Delta T}{T} = \frac{0.1}{200} = 0.05\%
  4. Δgg=0.1%+2(0.05%)=0.2%\frac{\Delta g}{g} = 0.1\% + 2(0.05\%) = 0.2\%
  5. So the answer is (c) 0.2%0.2\%.
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