Question

Consider a particle of mass m moving in a plane with a constant radial speed $\dot{r}$ and a constant angular speed $\dot{\theta}$. The acceleration of the particle in (r,$\theta$) coordinates is

• A. $2r\dot{\theta}^2\hat{r}-\dot{r}\dot{\theta}\hat{\theta}$
• B. $-r\dot{\theta}^2\hat{r}+2\dot{r}\dot{\theta}\hat{\theta}$
• C. $\ddot{r}\hat{r}+r\ddot{\theta}\hat{\theta}$
• D. $\ddot{r}\theta\hat{r}+r\ddot{\theta}\hat{\theta}$

Answer 1

Answer: (B)

$-r\dot{\theta}^2\hat{r}+2\dot{r}\dot{\theta}\hat{\theta}$

Answer 2

The correct answer is (B) : $-r\dot{\theta}^2\hat{r}+2\dot{r}\dot{\theta}\hat{\theta}$