v=πrTv=\frac{\pi r}{T}v=Tπr
v=2πrTv=\frac{2 \pi r}{T}v=T2πr
V=T2πrV=\frac{T}{2 \pi r}V=2πrT
v=Tπrv=\frac{T}{\pi r}v=πrT