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Bernoulli's Theorem and Applications

Questions covering Bernoulli's theorem, fluid pressure variations, and practical applications such as venturi meters and airfoil lift. Tests understanding of energy conservation in fluid flow.

50 questions

A spray tube (9cm2) has 45 holes of diameter 0.6mm. If the flow speed is 2.0m/min, what is the ejection speed?

A1v1 = A2v2, v1 = 2.0m/min = 0.0333m/s, A1 = 9×10−4m2. Hole area: Ah = π(0.3×10−3)2, total A2 = 45×π×9×10−8≈1.272×10−5m2. v2 = 9×10−4×0.03331.272×10−5≈2.36m/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2.4 m/s. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

Water flows at 1.5m/s at 2.5m height with pressure 1.8×105Pa. What is the pressure at 0.5m height with speed 2.5m/s? (ρ\

Bernoulli’s: P1+12ρv12+ρgh1 = P2+12ρv22+ρgh2. Left: 1.8×105+12×1000×2.25+1000×10×2.5 = 1.8×105+1125+25000 = 2.06125×105. Right: P2+12×1000×6.25+1000×10×0.5 = P2+3125+5000 = P2+8125. 2.06125×105 = P2+8125, P2 = 1.98×105Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.98 × 10⁵ 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.

An aircraft (m\=4.0×105kg, wing area 600m2) flies level. What is the pressure difference across the wings? (Take g\=9.8m

ΔP⋅A = mg. mg = 4.0×105×9.8 = 3.92×106N, A = 600m2. ΔP = 3.92×106600 = 6533.33Pa≈6533Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 6533 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.

A metal plate of area 0.05m2 moves over a liquid film (η\=0.02Pa s) of thickness 0.2mm at 0.5m/s. What is the force requ

Viscous force: F = ηvAl. η = 0.02Pa s, v = 0.5m/s, A = 0.05m2, l = 0.2×10−3m. F = 0.02×0.5×0.050.2×10−3 = 0.02×125 = 2.5N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2.5 N. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

A pipe’s cross-sectional area decreases from 0.04m2 to 0.01m2. If the speed at the larger end is 2.5m/s, what is the spe

Continuity equation: A1v1 = A2v2. A1 = 0.04m2, v1 = 2.5m/s, A2 = 0.01m2. v2 = A1v1A2 = 0.04×2.50.01 = 10m/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 10 m/s. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.

The pressure at a depth of 3m in ethyl alcohol (ρ\=806kg/m3) is measured with atmospheric pressure as 1.01×105Pa. What i

Total pressure: P = Pa+ρgh. Pa = 1.01×105Pa, ρ = 806kg/m3, g = 10m/s2, h = 3m. P = 1.01×105+806×10×3 = 1.01×105+24180 = 1.2518×105Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.25 × 10⁵ 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.

A bubble of radius 3.5mm is blown at 15cm depth in water (ρ\=1000kg/m3, S\=0.0727N/m). What is the total pressure inside

Pi = Pa+ρgh+2Sr. Pa = 1.01×105Pa, ρgh = 1000×9.8×0.15 = 1470Pa. 2Sr = 2×0.07273.5×10−3 = 41.54Pa. Pi = 1.01×105+1470+41.54 = 1.02471×105Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.025 × 10⁵ 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.

A soap bubble of radius 8mm has a surface tension of 0.027N/m. What is the excess pressure inside?

Excess pressure in a bubble: ΔP = 4Sr. S = 0.027N/m, r = 8×10−3m. ΔP = 4×0.0278×10−3 = 13.5Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 13.5 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.

What is the total pressure at a depth of 4m in seawater (ρ\=1.03×103kg/m3) if atmospheric pressure is 1.01×105Pa? (Take

Total pressure: P = Pa+ρgh. Pa = 1.01×105Pa, ρ = 1.03×103kg/m3, g = 9.8m/s2, h = 4m. P = 1.01×105+1.03×103×9.8×4 = 1.01×105+40376 = 1.41376×105Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.41 × 10⁵ Pa. This satisfies dimensional consistency and physical conditions given, so option A is scientifically correct.

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