Find the viscous drag between the two liquid layers each of area 100 `cm^(2)`, and having relative velocity 8 cm `s^(-1)`. The viscosity of the liquid is 0.004 PI and the layers are separated by a distance 4 cm.

Explanation

To find the viscous drag between the two liquid layers, we can use the formula for viscous drag (also known as viscous force):

\[ F = \eta \cdot A \cdot \frac{dv}{dx} \]

where:
- \( F \) is the viscous drag force,
- \( \eta \) is the viscosity of the liquid,
- \( A \) is the area of the layers,
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