A metal block of base area 0.20 m² is placed on a table, as shown in figure. A liquid film of thickness 0.25 mm is inserted between the block and the table. The block is pushed by a horizontal force of 0.1 N and moves with a constant speed. If the viscosity of the liquid is 5.0 × 10⁻³ Pa s, the speed of block is ______ × 10⁻³ m/s. Image
Physics · Circular Motion
JEE Mains 29 January 2023 Shift 2 Evening Shift

Question

A metal block of base area 0.20 m² is placed on a table, as shown in figure. A liquid film of thickness 0.25 mm is inserted between the block and the table. The block is pushed by a horizontal force of 0.1 N and moves with a constant speed. If the viscosity of the liquid is 5.0 × 10⁻³ Pa s, the speed of block is ______ × 10⁻³ m/s. Image

Physics · Circular Motion

G1 Physics · Accepted Answer

Viscous force F = ηA(v/h). Therefore v = Fh/(ηA) = [0.1×0.25×10⁻³]/[(5×10⁻³)(0.20)] = 0.025 m s⁻¹ = 25×10⁻³ m s⁻¹.