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A cubic block of side L and mass M is dragged over an oil film across table by a string connects to a hanging block of mass m as shown in figure. The Newtonian oil film of thickness h has dynamic viscosity μ and the flow condition is laminar. The acceleration due to gravity is g. The steady state velocity V of block is
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Mgh μL²
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Mgh μ
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mgh μL²
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mgh μ
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Correct Option: C
| τ = μ |  |  | ||
| dy |
du = V – O – V
dy = h
| τ = u | ...(1) | |
| h |
| Also , τ = | ||
| A |
where F = mg , A = L2
| ∴ τ = | ......(2) | |
| L2 |
By (1) (2), we get
| V = | ||
| uL2 |
