# Dimension of angular displacement, velocity and acceleration

1. Jan 16, 2007

### grigabuoy

1. The problem statement, all variables and given/known data

I have a homework question that I do not understand. I have searched everwhere for the answer. I think I did not find the answer because I am do not understnad waht the question is asking for. Some help would be greatly appreciated.

The question is: What are the dimensions of angular displacement, and angular velocity, and angular acceleration?

Can someone in simple terms explain what I am suppose to be looking for. The section in my text book made no reference to dimension of anything.

Thanks

2. Jan 16, 2007

### dontdisturbmycircles

I am pretty sure they are looking for the dimensional units for angular motion. Have you seen dimensional analysis before?

3. Jan 16, 2007

### Decan

I agree with the above poster....look at your text, see the appropriate equation and solve for the units.

For example, E = Fd, so the units are N.m = J

4. Jan 16, 2007

### dontdisturbmycircles

Sorry Decan, I mean no disrespect at all but I think that they may be asking for something different.

For example, the dimensions of velocity are $$\frac{L}{T}$$ where L represents the dimension of length and T represents the dimension of time (which should make sense). The dimensions of acceleration are $$\frac{L}{T^{2}}$$ which should also make sense.

I have not studied angular motion grigabuoy so I am afraid that I will not be comfortable with giving you a definite answer to your question, hopefully someone else can fill in the gaps in this regard.

By the way, if you haven't learned about dimensional analysis yet, do so quickly. It is very useful for ensuring that your equations are correct on tests, as well as other things.

edit: removed my assumed dimensional units once Kurdt clarified, thanks.

Last edited: Jan 16, 2007
5. Jan 16, 2007

### Kurdt

Staff Emeritus
Angle is considered one of the fundamental dimensions along with length, time and mass. Like the post above all you must do it seems is state the dimensions of the quantities based upon previous knowledge. Angular velocity and acceleration are analagous to normal velocity and acceleration.

6. Jan 16, 2007

### civil_dude

I agree that the term 'dimension' is not the same as units. The dimensions for angular displacement would be angle; angular velocity would be angle per unit time; and angular velocity would be angle per unit time per unit time.

The working unit for angle is radians, which is unitless. The working unit for time is second.

The units for the above then would be radians, radians/s and radians/s^2.

7. Jan 16, 2007

### Decan

Not a problem...I misunderstood the question :)

8. Jan 16, 2007

### grigabuoy

Thanks

I think I finally got what I needed. If there is anything else I will be sure to ask. This information gives me something to run with.

Thanks,
grigabuoy