If the radius of a sphere is measured to be (2.1±0.05) cm. Calculate the surface area (in cm^2 ) .

Correct answer: (B) 55.44 ± 2.64. S=4πr^2=4×22/7×(2.1)^2 =55.44cm^2 (ΔS)/S=2(Δr)/r ΔS=2(Δr)/rS =(2×0.05×55.44)/2.1=2.64 ∴ ΔS=(55.44±2.64) cm^2

Q2 / 16 · NTA Abhyas (NEET) 2020 · Physics · Experimental Physics

If the radius of a sphere is measured to be $(2.1 \pm 0.05) cm .$ Calculate the surface area (in ${cm}^{2}$ ) .

$S = 4 {πr}^{2} = 4 \times \frac{22}{7} \times (2.1)^{2}$

$= 55.44 {cm}^{2}$

$\frac{ΔS}{S} = 2 (\frac{Δr}{r})$

$ΔS = 2 (\frac{Δr}{r}) S$

$= \frac{2 \times 0.05 \times 55.44}{2.1} = 2.64$

$∴ ΔS = (55.44 \pm 2.64) {cm}^{2}$

Hence, the correct answer is option: 'B'.