Linear Drag Force Homework: Acceleration & Constant Speed Calculations

[antoman]

Homework Statement

We sink ball with density 1450 kg/m^3 in some liquid with density 1400 kg/m^3

a) What's acceleration in moment we drop the ball?
b) With what constant speed will the ball sink in balace? Assuming that the drag force is linear. Radius of ball is 3mm and viscosity of liquid is 200 Pa s.

Homework Equations

a=(g*(ρb-ρl))/ρb

The Attempt at a Solution

a... acceleration
ρb=1450 kg/m^3
ρl=1400 kg/m^3
g=9,81 m/s^2

a) That's easy, using the formula and you get a=0,338 m/s^2
b) Need help here, no idea how to solve

 

[Chestermiller]

Homework Statement

We sink ball with density 1450 kg/m^3 in some liquid with density 1400 kg/m^3

a) What's acceleration in moment we drop the ball?
b) With what constant speed will the ball sink in balace? Assuming that the drag force is linear. Radius of ball is 3mm and viscosity of liquid is 200 Pa s.

Homework Equations

a=(g*(ρb-ρl))/ρb

The Attempt at a Solution

a... acceleration
ρb=1450 kg/m^3
ρl=1400 kg/m^3
g=9,81 m/s^2

a) That's easy, using the formula and you get a=0,338 m/s^2
b) Need help here, no idea how to solve

Have you learned the equation for calculating the viscous drag force (in creeping flow) on a sphere of diameter, when the sphere is moving with a velocity v relative to the viscous fluid?

 

[antoman]

Have you learned the equation for calculating the viscous drag force (in creeping flow) on a sphere of diameter, when the sphere is moving with a velocity v relative to the viscous fluid?

If you mean in colledge probably yes, but me personaly don't know that equation.

 

[Chestermiller]

If you mean in colledge probably yes, but me personaly don't know that equation.

Google Stokes Law.