If the radius of a sphere is measured to be ( 2 . 1 ± 0 . 05 ) cm . Calculate the surface area (in cm 2 ) .

S = 4 πr 2 = 4 × 22 7 × ( 2 . 1 ) 2 = 55 . 44 cm 2 ΔS S = 2 Δr r ΔS = 2 Δr r S = 2 × 0 . 05 × 55 . 44 2 . 1 = 2 . 64 ∴ ΔS = ( 55 . 44 ± 2 . 64 ) cm 2

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PhysicsPractical physicsMiscellaneousEasy2 minPYQ_2020

PhysicsEasysingle choice

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

Answer:

Solution:

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

$= 55.44 {cm}^{2}$

$\frac{ΔS}{S} = 2 (\frac{Δr}{r})$

$ΔS = 2 (\frac{Δr}{r}) S$

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

$∴ ΔS = (55.44 \pm 2.64) {cm}^{2}$

Stream:NTA_ABHYAS_NEETSubject:PhysicsTopic:Practical physicsSubtopic:Miscellaneous

⏱ 2mℹ️ Source: PYQ_2020

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