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#plate movement

4 public questions tagged with this topic.

Viscosity, Stokes' Law and Reynolds Number

A plate of area 0.09m2 moves at 0.5m/s over a 0.6mm thick machine oil film (η\=0.113Pa s). What force is required?

Viscous force: F = ηvAl. η = 0.113Pa s, v = 0.5m/s, A = 0.09m2, l = 0.6×10−3m. F = 0.113×0.5×0.090.6×10−3 = 0.113×75 = 8.475N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 8.5 N. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

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

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Equation of Continuity and Flow Rate

A plate of area 0.05m2 moves at 0.7m/s over a 0.8mm thick water film (η\=1.0×10−3Pa s). What force is required?

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.

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Surface Tension, Capillarity and Excess Pressure

A plate of area 0.06m2 moves at 0.9m/s over a 0.5mm thick honey film (η\=0.2Pa s). What force is required?

Viscous force: F = ηvAl. η = 0.2Pa s, v = 0.9m/s, A = 0.06m2, l = 0.5×10−3m. F = 0.2×0.9×0.060.5×10−3 = 0.2×108 = 21.6N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 22 N. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

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

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Fluid Pressure, Pascal's Law and Manometers

A plate of area 0.06m2 moves at 0.6m/s over a 0.4mm thick glycerine film (η\=0.83Pa s). What force is required?

Viscous force: F = ηvAl. η = 0.83Pa s, v = 0.6m/s, A = 0.06m2, l = 0.4×10−3m. F = 0.83×0.6×0.060.4×10−3 = 0.83×90 = 74.7N. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 74.7 N. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

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

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