- #1

doktorwho

- 181

- 6

## Homework Statement

Given the ## r(t) = ae^{kt}## , ##θ(t)=kt## find the velocity function that is dependent on ##r##.

##v(r)=?##

## Homework Equations

3. The Attempt at a Solution [/B]

My attempt:

1)##r(t) = ae^{kt}##

2)##{\dot r(t)} = ake^{kt}##

From the first equation:

##\ln {\frac{r(t)}{a}}=\ln e^{kt}##

##\ln {\frac{r(t)}{a}}=kt##

##t=\frac{\ln {\frac{r(t)}{a}}}{k}##

Replacing the ##t## in the second equation i get:

##{\dot r}=akr##

Shouldn't this be the answer? In the answers it says ##{\dot r}=\sqrt2r##?

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