Calculating Natural Frequency in English Units

To calculate natural frequency in English units, you have to
1) convert the weight of the unit into slugs
2) convert stiffness from (lb/in) into (lb/ft), b/c slugs is in (lbf*s^2/ft)

Also, don't forget to multiply by (1/(2*pi)) to get natrual frequency in Hz!

Ex:

k = 1000; %lb/in
m = 30; %lb

k = k*12; %convert stiffness into lbf/ft
m = m*0.031081; %convert lb into slugs (lbf*s^2/ft)
wn = (1/(2*pi))*sqrt(k/m); %natrual frequency