For a particle in uniform circular motion,the acceleration $\vec{a}$ at any point $P (R, \theta)$ on the circular path of radius $R$ is (when $\theta$ is measured from the positive $x$-axis and $v$ is uniform speed):

• A
  $-\frac{v^{2}}{R} \sin \theta \hat{i} + \frac{v^{2}}{R} \cos \theta \hat{j}$
• B
  $-\frac{v^{2}}{R} \cos \theta \hat{i} + \frac{v^{2}}{R} \sin \theta \hat{j}$
• C
  $-\frac{v^{2}}{R} \cos \theta \hat{i} - \frac{v^{2}}{R} \sin \theta \hat{j}$
• D
  $-\frac{v^{2}}{R} \hat{i} + \frac{v^{2}}{R} \hat{j}$