Question

1-a body with m = 3 Kg and it's velocity at certain time is 9 m/s and he cross a distance 18 m at 3 second ,

tell what is the force acting on it and find the magnitude of the force .

2- a thin plate with area 0.08 m² , isolated from another plate by liquid layer with thickness 3 mm.

if a tangent force acting on it by 6.3 N the it moved by velocity 33 cm/s, calculate the viscosity coefficient by ( Poise (unit) )

Answer 1

m = 3 kg

s = 18 m

u = 9 m/s

v = 0 m/s

where a is acceleration,

from this equation, we get a = -2.25 , negative sign represents it is a stopping the particle.

|Force| = m*|a| = 3*2.25 = 6.75 N

Part 2:

We know,

where F is the tangential force = 6.3 N

A is the plate area = 0.08 m2

dz is the thickness of fluid = m

v = m/s

velocity of fluid touching the stationary plate = 0 m/s

dv = m/s

Putting the values in the equation, we get

6.3 / (0.08 * 110) = 0.7159 deca poise = 7.159 poise