# Angular speed

1. Nov 28, 2015

### Cesare

Good morning,

I have an iron bar (35 cm long) hinged on an axis. The path of this bar is limited to 45 degrees.
I have to measure the angular velocity of the bar when it rotates 45 degrees. I need to get a graph of variation of the angular velocity along the 45 degree paths. The time taken to cover 45 degrees, is about 20ms

Can You help me?
Cesar

2. Nov 28, 2015

### BvU

Ave Cesar,

This is still rather ambiguous. Can you explain a bit clearer and post a picture ?

Last edited: Nov 28, 2015
3. Nov 28, 2015

### Cesare

I have attached a photo.

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• ###### Untitled-1.jpg
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4. Nov 28, 2015

### Staff: Mentor

I would put a protractor in the background, then take a video. From the video you can see change in angle frame-by-frame.

5. Nov 29, 2015

### Cesare

I need angular velocity and not only angle.

6. Nov 29, 2015

### BvU

And what is it that causes the anglar motion ? Where does the angular motion starr ?
Where is the 45 degrees limitation you mentioned in your post #1 ?
Is there any source of friction at all ?

7. Nov 29, 2015

### Staff: Mentor

If your video takes 30 frames per second, and if you measure a difference A in the angle from one frame to the next frame, then angular velocity is 30A degrees per second.

8. Nov 29, 2015

### Cesare

The angular motion is caused from a click of a spring that I can not known.

9. Nov 29, 2015

### Staff: Mentor

If you want a better answer, you have to explain more about what you're doing.