The image above represents polar moment of inertia.

To compute for polar moment of inertia, one essential parameter is needed and this parameter is **Radius (r).**

The formula for calculating polar moment of inertia:

J = ^{πr4}/_{2}

Where:

J = Polar Moment of Inertia

r = Radius

Let’s solve an example;

Find the polar moment of inertia when the radius is 22.

This implies that;

r = Radius = 22

J = ^{πr4}/_{2}

J = ^{π(22)4}/_{2}

J = ^{π(234256)}/_{2}

J = ^{735936.928}/_{2}

J = 367968.46

Therefore, the **polar moment of inertia **is **367968.46 m ^{4}.**

**Calculating the Radius when the Polar Moment of Inertia is Given.**

r = 4√(^{2J} / _{π})

Where;

r = Radius

J = Polar Moment of Inertia

Let’s solve an example;

Given that the polar moment of inertia is 30. Find the radius?

This implies that;

J = Polar Moment of Inertia = 30

r = 4√(^{2J} / _{π})

r = 4√(^{2 x 30} / _{π})

r = 4√(^{60} / _{π})

r = 4√19.09

r = 17.47

Therefore, the **radius **is **17.47 m.**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the polar moment of inertia.

To get the answer and workings of the polar moment of inertia 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 **for** NGN 2,000 **per** annum** 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 **Material Selection**** **under **Materials and Metallurgical**

Now, Click on **Polar Moment of Inertia **under **Material Selection**

The screenshot below displays the page or activity to enter your valus, to get the answer for the polar moment of inertia according to the respective parameter which is the **Radius (r).**

Now, enter the value appropriately and accordingly for the parameter as required by the **Radius (r) **is **22.**

Finally, Click on Calculate

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