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#ethanol drop

2 public questions tagged with this topic.

Viscosity, Stokes' Law and Reynolds Number

What is the excess pressure inside an ethanol drop of radius 2.2mm at 20∘C? (Surface tension = 0.0227N/m)

Excess pressure: ΔP = 2Sr. S = 0.0227N/m, r = 2.2×10−3m. ΔP = 2×0.02272.2×10−3 = 20.64Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 22 Pa. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

Ref: NCBI Bookshelf, Ideal Gas Law: P1V1/T1 = P2V2/T2.

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Fluid Pressure, Pascal's Law and Manometers

What is the excess pressure inside an ethanol drop of radius 1.5mm at 20∘C? (Surface tension = 0.0227N/m)

Excess pressure: ΔP = 2Sr. S = 0.0227N/m, r = 1.5×10−3m. ΔP = 2×0.02271.5×10−3 = 30.27Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 30 Pa. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: NCBI Bookshelf, Ideal Gas Law: P1V1/T1 = P2V2/T2.

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