Questions focused on fluid dynamics, including the continuity equation, volume flow rate, and steady flow in pipes and channels. Tests problem-solving skills in fluid mechanics.
Stokes’ law: F = 6πηav. η = 0.2Pa s, a = 0.04m, v = 0.12m/s. F = 6×3.14×0.2×0.04×0.12 = 0.1809N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 0.18 N. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.
Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.
Viscous force: F = ηvAl. η = 0.83Pa s, v = 0.8m/s, A = 0.08m2, l = 0.7×10−3m. F = 0.83×0.8×0.080.7×10−3 = 0.83×91.43 = 75.89N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 76 N. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.
Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.
ΔP⋅A = mg. mg = 2.0×105×9.8 = 1.96×106N, A = 400m2. ΔP = 1.96×106400 = 4900Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 4900 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.
Excess pressure in a bubble: ΔP = 4Sr. S = 0.028N/m, r = 7×10−3m. ΔP = 4×0.0287×10−3 = 16Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 16 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.
Terminal velocity occurs when the viscous force (proportional to velocity) equals the net gravitational force, resulting in zero acceleration and constant speed, as per Stokes’ law. As per NCERT, applying relevant law/formula with correct units and sign convention leads to It occurs when forces balance. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.
Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.
Gauge pressure: Pg = ρgh. ρ = 1.06×103kg/m3, g = 10m/s2, h = 2.4m. Pg = 1.06×103×10×2.4 = 25440Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2.5 × 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.
The angle of contact depends on the relative strength of adhesive (liquid-solid) and cohesive (liquid-liquid) forces, determining wetting behavior (acute for wetting, obtuse for non-wetting). As per NCERT, applying relevant law/formula with correct units and sign convention leads to It depends on adhesive and cohesive forces. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.
Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.
Viscous force: F = ηvAl. η = 1.0×10−3Pa s, v = 0.7m/s, A = 0.05m2, l = 0.8×10−3m. F = 1.0×10−3×0.7×0.050.8×10−3 = 1.0×10−3×43.75 = 0.04375N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 0.044 N. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.
Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.
ΔP⋅A = mg. mg = 2.8×105×9.8 = 2.744×106N, A = 480m2. ΔP = 2.744×106480 = 5716.67Pa≈5717Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 5717 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.
Gauge pressure: Pg = ρgh. ρ = 13.6×103kg/m3, g = 10m/s2, h = 2.5m. Pg = 13.6×103×10×2.5 = 3.4×105Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 3.4 × 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.
Total pressure: P = Pa+ρgh. Pa = 1.01×105Pa, ρ = 1.43kg/m3, g = 9.8m/s2, h = 1.8m. P = 1.01×105+1.43×9.8×1.8 = 1.01×105+25.21 = 1.0102521×105Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.01 × 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.
Torricelli’s law: v = 2gh. g = 9.8m/s2, h = 1.3m. v = 2×9.8×1.3 = 25.48≈5.05m/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 5.0 m/s. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.
Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.
