Question

A metal plate, 10 cm square, rests on a 2 mm thick castor oil layer. Find the horizontal force needed to move the plate with a speed of 3 cm/s. The coefficient of viscosity of castor oil is 15 poise.

A. 34,000 dyn
B. 25,200 dyn
C. 32,500 dyn
D. 22,500 dyn

Answer 1

To find the horizontal force needed to move the metal plate with a speed of 3 cm/s, use the equation for the drag force due to the viscosity of a fluid.

Step-by-step explanation:

To find the horizontal force needed to move the metal plate with a speed of 3 cm/s, we need to use the equation for the drag force due to the viscosity of a fluid. The drag force (Fd) is given by the equation Fd = ηAv, where η is the coefficient of viscosity, A is the contact area, and v is the speed of the plate. In this case, the contact area is 10 cm² and the speed is 3 cm/s. Given that the coefficient of viscosity of castor oil is 15 poise, we can calculate the drag force using the formula.

Fd = (η)(A)(v) = (15 poise)(10 cm²)(3 cm/s) = 450 poise.cm²/s

Therefore, the horizontal force needed to move the plate with a speed of 3 cm/s is 450 poise.cm²/s.