The figure

helps to establish the relationship between force and

Options

A. area of contact
B. velocity gradient
C. coefficient of viscosity
D. both (a) and (b) .

Answer

D

Explanation

This figure clearly helps to establish the relation that force is directly proportional to area of contact and velocity gradient.
`f prop A, f prop (du)/(dz)`
`therefore f prop A (du)/(dz)`
`f = eta A(du)/(dz)`
Where, `eta` = coefficient of viscosity.
A = Area of contact.
`(du)/(dz)`= velocity gradient.