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#fluid pressure

38 public questions tagged with this topic.

A manometer with whole blood (ρ\=1.06×103kg/m3) shows a height difference of 0.18m. What is the pressure difference? (Ta

ΔP = ρgh. ρ = 1.06×103kg/m3, g = 10m/s2, h = 0.18m. ΔP = 1.06×103×10×0.18 = 1908Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1908 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 force on a submarine window (0.08m2) at 300m depth in seawater (ρ\=1.03×103kg/m3), interior at atmospheric p

Gauge pressure: Pg = ρgh = 1.03×103×10×300 = 3.09×106Pa. F = PgA = 3.09×106×0.08 = 2.472×105N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2.47 × 10⁵ N. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

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

Water (ρ\=1000kg/m3) flows horizontally at 3.5m/s with pressure 1.7×105Pa. If the speed rises to 6m/s, what is the new p

Bernoulli’s equation: P1+12ρv12 = P2+12ρv22. P1 = 1.7×105Pa, v1 = 3.5m/s, v2 = 6m/s, ρ = 1000kg/m3. P2 = 1.7×105+12×1000(12.25−36) = 1.7×105−11875 = 1.58125×105Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.58 × 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.

What is the total pressure at a depth of 3.4m in seawater (ρ\=1.03×103kg/m3) with atmospheric pressure 1.01×105Pa? (Take

Total pressure: P = Pa+ρgh. Pa = 1.01×105Pa, ρ = 1.03×103kg/m3, g = 9.8m/s2, h = 3.4m. P = 1.01×105+1.03×103×9.8×3.4 = 1.01×105+34319.6 = 1.353196×105Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.35 × 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 mercury barometer shows a height of 75cm at sea level. What is the atmospheric pressure? (ρ\=13.6×103kg/m3, g\=10m/s2)

Pa = ρgh. ρ = 13.6×103kg/m3, g = 10m/s2, h = 0.75m. Pa = 13.6×103×10×0.75 = 1.02×105Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.02 × 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.

A container has whole blood (ρ\=1.06×103kg/m3) up to 1.5m. What is the gauge pressure at the bottom? (Take g\=9.8m/s2)

Gauge pressure: Pg = ρgh. ρ = 1.06×103kg/m3, g = 9.8m/s2, h = 1.5m. Pg = 1.06×103×9.8×1.5 = 15582Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.56 × 10⁴ 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.

Why does the pressure in a fluid decrease when its speed increases in a horizontal pipe?

Bernoulli’s principle states that in steady flow, an increase in kinetic energy (12ρv2) corresponds to a decrease in pressure energy, as total energy is conserved along a horizontal streamline. As per NCERT, applying relevant law/formula with correct units and sign convention leads to Because of energy conservation. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

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

A hydraulic press uses a small piston of area 0.008m2 to exert 120N. What force is produced by a large piston of area 0.

Pascal’s law: P = F1A1 = F2A2. F2 = F1×A2A1. F1 = 120N, A1 = 0.008m2, A2 = 0.032m2. F2 = 120×0.0320.008 = 120×4 = 480N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 480 N. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

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

A bubble of radius 4mm is formed at 50cm depth in a soap solution (ρ\=1.2×103kg/m3, S\=0.025N/m). What is the total pres

Pi = Pa+ρgh+2Sr. Pa = 1.01×105Pa, ρgh = 1.2×103×9.8×0.5 = 5880Pa. 2Sr = 2×0.0254×10−3 = 12.5Pa. Pi = 1.01×105+5880+12.5 = 1.06892×105Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.069 × 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.

Why do fluids exert pressure only normal to a surface at rest?

In a fluid at rest, any tangential (shear) force would cause the fluid to flow due to its inability to resist shear stress. According to Newton’s third law, if a tangential force existed, the fluid would exert an equal and opposite force, leading to motion. Since the fluid is at rest, no such motion occurs, and the force must be normal to the surface.

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

What is the force on a submarine window (0.05m2) at 600m depth in seawater (ρ\=1.03×103kg/m3), interior at atmospheric p

Gauge pressure: Pg = ρgh = 1.03×103×10×600 = 6.18×106Pa. F = PgA = 6.18×106×0.05 = 3.09×105N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 3.09 × 10⁵ N. 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 fluid flows through a pipe with speeds v1\=2m/s at height h1\=1m and v2\=4m/s at h2\=0m. If P1\=1.2×105Pa, find P2. (ρ

Bernoulli’s equation: P1+12ρv12+ρgh1 = P2+12ρv22+ρgh2. P1 = 1.2×105, v1 = 2m/s, h1 = 1m, v2 = 4m/s, h2 = 0m. Left: 1.2×105+12×1000×4+1000×10×1 = 1.2×105+2000+10000 = 1.32×105. Right: P2+12×1000×16 = P2+8000. 1.32×105 = P2+8000, P2 = 1.24×105Pa.

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