# Having trouble converting rpm to 1/s using unitConvert from symunit

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SamuLibero on 8 Mar 2023
Commented: David Hill on 8 Mar 2023
Hi guys,
I'm using symunit for a project where I have to calculate the dimensions of an impeller. I'm using symunit to convert all the results accordingly to the book i'm refering to. But i'm having big problems working with it as soon as I try to convert rpm to 1/s.
u = symunit;
n = 2950 * u.rpm; % Given
w = vpa(unitConvert(n,(1/u.s))); % I need the angular velocity in 1/s for the next steps
For "w" I get 308.92 rad/s. Which if devided by rad (2*pi) would give the right result 49.01. But i don't understand why despide telling that I want the output in 1/s i get rad/s. Do I have to do the conversion manually every time or am I using unitConvert wrong?
Thank you for your help, I appreciate it! :)

David Hill on 8 Mar 2023
You want rps
u = symunit;
n = 2950 * u.rpm;
w = vpa(unitConvert(n,u.rps))
w =
##### 2 CommentsShow 1 older commentHide 1 older comment
David Hill on 8 Mar 2023
Not sure, but multiplying by 2*pi*u.rad will take care of it. Maybe someone else has more insight. I don't like using symbolic units.
u = symunit;
n = 2950 * u.rpm;
w = vpa(unitConvert(n,u.rps));
P_imp = 5 * u.W
P_imp =
M_imp =

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