Question

A metal plate 5cm by 5cm rests on a layer of castor oil 1mm thick whose coefficient of viscosity is 1.55Nsm^-2. Calculate the magnitude of applied force.

Answer 1

Answer:

0.0775 N

Explanation:

Given A metal plate 5 cm by 5 cm rests on a layer of castor oil 1 mm thick whose coefficient of viscosity is 1.55 N s m^-2. Calculate the horizontal force to move the plate with a speed of 2 m/s.

Given length of metal plate = 5 cm and length of metal plate = 5 cm

Area of metal plate = length x breadth

                   A = 5 x 5

                    A = 25 sq cm

Co efficient of viscosity = ɳ = 1.55 Ns/m^2

dx = small thickness of layer = 1 mm = 10^-3 m

small velocity = dv = 2 x 10^-2 m/s

Now velocity gradient = dv/dx = 2 x 10^-2 / 10^-3

                                                      = 2 x 10

                                                      = 20 m

So horizontal force F = ɳAdv/dx

                                F = 1.55 x 25 x 10^-4 x 2 x 10^-2 / 10^-3

                                     = 1.55 x 25 x 10^-4 x 20  

                                F = 0.0775 N

Answer 2

Hope it helps!!

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