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JEE Main 20266 AprilMorning Shift
Exam
JEE Main
Year
2026
Date
6 April
Shift
Morning Shift
Subject
Physics
Chapter
Mathematics in Physics

JEE Main 2026 · 6 April · Morning Shift · Physics · Mathematics in Physics

The density of a uniform cylinder is determined by measuring its...

The density ρ\rho of a uniform cylinder is determined by measuring its mass mm, length ll and diameter dd. The measured values of mm, ll and dd are 97.42±0.0297.42 \pm 0.02 g, 8.35±0.058.35 \pm 0.05 mm and 20.20±0.0220.20 \pm 0.02 mm, respectively. Calculated percentage fractional error in ρ\rho is _______.

Options

  1. A0.63%0.63\%
  2. B0.82%0.82\%
  3. C0.72%0.72\%
  4. D0.25%0.25\%

Correct answer

B. 0.82%0.82\%

Step-by-step solution

The density of a uniform cylinder is given by ρ=mV=4mπd2l\rho = \dfrac{m}{V} = \dfrac{4m}{\pi d^2 l}

The percentage fractional error in density is given by:

Δρρ×100=(Δmm+2Δdd+Δll)×100\dfrac{\Delta \rho}{\rho} \times 100 = \left( \dfrac{\Delta m}{m} + 2\dfrac{\Delta d}{d} + \dfrac{\Delta l}{l} \right) \times 100

Substituting the given values:

Δρρ×100=(0.0297.42+2×0.0220.20+0.058.35)×100\dfrac{\Delta \rho}{\rho} \times 100 = \left( \dfrac{0.02}{97.42} + 2 \times \dfrac{0.02}{20.20} + \dfrac{0.05}{8.35} \right) \times 100

Δρρ×100=(0.000205+0.00198+0.005988)×100\dfrac{\Delta \rho}{\rho} \times 100 = \left( 0.000205 + 0.00198 + 0.005988 \right) \times 100

Δρρ×100=0.008173×100=0.8173%\dfrac{\Delta \rho}{\rho} \times 100 = 0.008173 \times 100 = 0.8173\%

Rounding off to two decimal places, the percentage error is 0.82%0.82\%.

Answer: 0.82%0.82\%
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