The image above represents drag force.

To compute for drag force, three essential parameters are needed and these parameters are **Particle Diameter (d), Fluid Viscosity (μ)** and **Terminal Velocity (v).**

The formula for calculating drag force:

D = 3π.dμv

Where:

D = Drag Force | Stoke’s Formula

d = Particle Diameter

μ = Fluid Viscosity

v = Terminal Velocity

Let’s solve an example;

Find the drag force when the particle diameter is 21, the fluid viscosity is 7 and the terminal velocity is 3.

This implies that;

d = Particle Diameter = 21

μ = Fluid Viscosity = 7

v = Terminal Velocity = 3

D = 3π.dμv

D = 3π.(21)(7)(3)

D = 3π.(441)

D = 4156.3

Therefore, the **drag force **is **4156.3 N.**

**Calculating the Particle Diameter when the Drag Force, the Fluid Viscosity and the Terminal Velocity is Given.**

d = ^{D} / _{3π.μv}

Where:

d = Particle Diameter

D = Drag Force | Stoke’s Formula

μ = Fluid Viscosity

v = Terminal Velocity

Let’s solve an example;

Find the particle diameter when the drag force is 30, the fluid viscosity is 4 and the terminal velocity is 2.

This implies that;

D = Drag Force | Stoke’s Formula = 30

μ = Fluid Viscosity = 4

v = Terminal Velocity = 2

d = ^{D} / _{3π.μv}

d = ^{30} / _{3π.(4)(2)}

d = ^{30} / _{75.4}

d = 0.39

Therefore, the **particle diameter **is **0.39.**

**Calculating the Fluid Viscosity when the Drag Force, the Particle Diameter and the Terminal Velocity is Given.**

μ = ^{D} / _{3π.dv}

Where:

μ = Fluid Viscosity

D = Drag Force | Stoke’s Formula

d = Particle Diameter

v = Terminal Velocity

Let’s solve an example;

Find the fluid viscosity when the drag force is 24, the particle diameter is 4 and the terminal velocity is 6.

This implies that;

D = Drag Force | Stoke’s Formula = 24

d = Particle Diameter = 4

v = Terminal Velocity = 6

μ = ^{D} / _{3π.dv}

μ = ^{24} / _{3π.(4)(6)}

μ = ^{24} / _{226.2}

μ = 0.11

Therefore, the **fluid viscosity **is **0.11.**

**Calculating the Terminal Velocity when the Drag Force, the Particle Diameter and the Fluid Viscosity is Given.**

v = ^{D} / _{3π.dμ}

Where:

v = Terminal Velocity

D = Drag Force | Stoke’s Formula

d = Particle Diameter

μ = Fluid Viscosity

Let’s solve an example;

Find the terminal velocity when the drag force is 44, the particle diameter is 8 and the fluid viscosity is 3.

This implies that;

D = Drag Force | Stoke’s Formula = 44

d = Particle Diameter = 8

μ = Fluid Viscosity = 3

v = ^{D} / _{3π.dμ}

v = ^{44} / _{3π.(8)(3)}

v = ^{44} / _{226.2}

v = 0.19

Therefore, the **terminal velocity **is **0.19.**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the drag force.

To get the answer and workings of the drag force using the **Nickzom Calculator – The Calculator Encyclopedia. **First, you need to obtain the app.

You can get this app via any of these means:

**Web** – https://www.nickzom.org/calculator-plus

To get access to the **professional **version via web, you need to **register** and **subscribe **to have utter access to all functionalities.

You can also try the **demo **version via https://www.nickzom.org/calculator

**Android (Paid)** – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator

**Android (Free)** – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator

**Apple (Paid)** – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8

Once, you have obtained the calculator encyclopedia app, proceed to the **Calculator Map, **then click on **Materials and Metallurgical **under **Engineering****.**

Now, Click on **Mineral Processing **under **Materials and Metallurgical**

Now, Click on **Drag Force** under **Mineral Processing**

The screenshot below displays the page or activity to enter your values, to get the answer for the drag force according to the respective parameter which is the **Particle Diameter (d), Fluid Viscosity (μ) and Terminal Velocity (v).**

Now, enter the values appropriately and accordingly for the parameters as required by the **Particle Diameter (d)** is **21**,** Fluid Viscosity (μ)** is **7**** and Terminal Velocity (v)** is **3**.

Finally, Click on Calculate

As you can see from the screenshot above, **Nickzom Calculator**– The Calculator Encyclopedia solves for the drag force and presents the formula, workings and steps too.