Understanding Rotational Velocity and Its Significance in Physics

[CoreanJesus]

As a student taking my first step into rotational physics in a classroom filled with students who have a year of this ahead of me I beg for help! :P

So what is Rotational velocity? What does it define? How do signs work with rotation? What does its acceleration mean? Angular Velocity is constant but velocity is not? When you solve rotation problems why must you change to radians? What is life?
Thank you very much for the generous soul who took time to answer this.

 

[singularity38]

Hi, I'm new here (and I'm not an english native speaker, so I apologize for any mistake), but I'm pretty sure you have to be more specific about your question. If you have so many doubts maybe a textbook could be more useful than a post written here.

 

[jbriggs444]

So what is Rotational velocity? What does it define? How do signs work with rotation? What does its acceleration mean? Angular Velocity is constant but velocity is not? When you solve rotation problems why must you change to radians? What is life?

You already know what rotation is, right? You have an object and you turn it. "Rotational velocity" or "angular velocity" is how fast you turn it. What angle it rotates through in a unit of time. In a first year physics course, you will be dealing primarily with rotation in two dimensions. That means that there are only two directions for a rotation: clockwise or counterclockwise. You pick a sign convention and make one positive. Then the other is negative.

An angular acceleration is the rate at which angular velocity changes. If something is spinning at a constant rate, its angular acceleration is zero. If its angular velocity is positive and getting larger slowly, its angular acceleration is positive and small.

Ordinary velocity and "angular velocity" are independent of one another. An object can be moving quickly while not rotating or rotating quickly while not otherwise moving.

Rotation problems work best in radians because the formulas are simpler. You can work with degrees. But then you have factors of $\frac{pi}{180}$ cluttering things up. You can work with rotations per minute (rpm) but then you have factors of $\frac{pi}{30}$ everywhere.

You'd probably be best served opening your textbook and reading the introduction to the chapter on rotation though.

 

[CWatters]

So what is Rotational velocity? What does it define?

Google Angular velocity
https://en.wikipedia.org/wiki/Angular_velocity

The units are typically Radians per Second.

How do signs work with rotation?

Typically you can choose to define either clockwise or anticlockwise as positive. It's good practice to state which direction you are taking to be positive at the start of any answer you give (unless it's defined in the question).

What does its acceleration mean? Angular Velocity is constant but velocity is not?

Angular acceleration is the rate of change of angular velocity. Just like linear acceleration is the rate of change of linear velocity.
The units are typically Radians per second per second (Radians per second²).

When you solve rotation problems why must you change to radians? What is life?
Thank you very much for the generous soul who took time to answer this.

Google Why use radians. The short answer is it makes sums easier. A degree is rather an arbitrary fraction of a circle, there is nothing special about 360, we could just as easily divide circles into 100 degrees. A radian relates angles to linear dimensions in a way that degrees don't.

 

[CoreanJesus]

I Love this Community!
Thank you everyone for your help, this helped me tremendously!
I just needed the simple facts laid out to get my bearing!

Also about textbooks...
I'm enrolled in AP Physics C and my teacher teaches stuff off his notes without a designated textbook. People who took Physic before have an easy time following him but for people like me its been a struggle...
Are there any good online textbooks or any cheap textbooks you guys might recommend for AP Physics C Course?

 

[Nugatory]

Also about textbooks...
I'm enrolled in AP Physics C and my teacher teaches stuff off his notes without a designated textbook. People who took Physic before have an easy time following him but for people like me its been a struggle...
Are there any good online textbooks or any cheap textbooks you guys might recommend for AP Physics C Course?

We have an entire subforum for that. Start here: https://www.physicsforums.com/forums/science-and-math-textbooks.21/

 

[lekh2003]

I Love this Community!
Thank you everyone for your help, this helped me tremendously!
I just needed the simple facts laid out to get my bearing!

Also about textbooks...
I'm enrolled in AP Physics C and my teacher teaches stuff off his notes without a designated textbook. People who took Physic before have an easy time following him but for people like me its been a struggle...
Are there any good online textbooks or any cheap textbooks you guys might recommend for AP Physics C Course?

This is the textbook I studied from when doing Honors Physics. It should cover most of the concepts in AP Physics as well:

http://fcis.aisdhaka.org/personal/chendricks/IB/Giancoli/Giancoli Chapters.html

The link has all the chapters in pdf form (it has rotational motion). It could also help you in the future.