Angular Displacement in Rotational Dynamics

[cscott]

Why do we use the angle as the base quantity in rotational dynamics instead of, perhaps, arc length? Is it because angular displacement is easier to measure? Would it make any sense to use arc length?

 

[ZapperZ]

Arc length depends on the radius that you choose, so you always have to indicate the radius you are using that corresponds to that arc length. Angular displacement doesn't.

Zz.

 

[cscott]

Arc length depends on the radius that you choose, so you always have to indicate the radius you are using that corresponds to that arc length. Angular displacement doesn't.

Zz.

Oh, that makes sense. Thanks!