I think I understand now. If we hold one constant (either v or w) while we change r, the other (w or v) has to change. Therefore we can only use one of the equations while r is changing.
Thanks you all for your helpful comments!
but both times isn't it given that both v and w are constant ? I know you only explicitly stated that either one or the other is "held constant" but isn't it true that both v and w will be constant in each situation? (when I say v I mean speed by the way).
Thanks you for your replies!
jbriggs, can you please elaborate on why w and v are held constant in cases 1 and 2 respectively.
Also, how do the two cases differ physically? It seems to me like the same thing is happening in both cases: a car is moving in a circle.
I am curious how to tell how centripetal accel. changes with radius since there are two equations I can look at
a = v2/r
I read on a thread that if v is constant then use the top equation and if w is constant then use the bottom equation. Is this true? If so, can you please give...