- #1

- 466

- 5

so i thought for the kinetic energy it would be..

K=[itex]\frac{1}{2}[/itex]m(r

^{2}[itex]\dot{θ}[/itex]

^{2})

since v2 = r

^{2}[itex]\dot{θ}[/itex]

^{2}

but no.. the kinetic energy was actually K=[itex]\frac{1}{2}[/itex]m([itex]\dot{r}[/itex]

^{2}+r

^{2}[itex]\dot{θ}[/itex]

^{2})

why?

the velocity vector of some particle can be described by [itex]\frac{d\vec{r}}{dt}[/itex]. the velocity vector can also be described by rω. Why combine the two? aren't the two velocity terms (in the actual answer) the same? so then wouldn't i end up with 2v? but this is probably wrong. why is this wrong/ why is that the right way?

thanks all