Correction SS-2395
5 votes
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New Dimensions for units: angle and angular velocity
Created by Martin Kraska on 9/9/2016 3:23 PM Last Updated by Martin Kraska on 3/9/2019 9:36 PM
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 Description

SMath shows angular units (°, rad, rev) as "dimensionless"  and angular velocity units like rpm, rph... as "frequency"

This frequently causes problems for newbies, example: http://en.smath.info/forum/yaf_postst7738_Units-mismatch-bug.aspx
 

1st Proposal: Add unit categories (dimensions)

angular velocity
angle

and do proper assignments of the relevant units.

This would be consistent with the already existing unit steradian, which has it's own dimension

The angular units currently are categorized as dimensionless.

2nd Proposal set default unit of results with dimension 1/Time to 1/s instead of Hz.

1/s is correct in some cases where Hz is plain wrong. Just type 1rpm= and you see what I mean.

The 1/s leaves it to the user to think of what 1 stands for. It could be radians, revolutions. Also strain rates (length change per length and time) have this dimension and Hz is inappropriate but 1/s is ok.

 
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    Martin Kraska (Saturday, March 9, 2019 9:30 PM) #

Are there major obstacles preventing the removal of Hz as default unit if dimension is 1/time?

This contributes to the angular velocity versus frequency confusion. Fixing this (and introducing the above-mentioned categories for units) could save a full handbook page.

    Jay Abel (Thursday, September 22, 2016 5:13 PM) #

For what my humble opinion is worth, I agree that angular frequency should be separate from frequency, and would be okay with either proposal, 2nd in the short term, 1st after careful consideration.