# Math Help - centripetal force

1. ## centripetal force

A body of mass 12 kg moves in a (counterclockwise) circular path of radius 11 meters centered at the origin, making one revolution every 10 seconds. We assume the circle is in the xy-plane, and so the third component may be ignored. At time t=0 the body is in the rightmost position (position with the largest x).
A. Compute the centripetal force acting on the body at time t.
,
B. Compute the magnitude of that force. = 52.11

i found part B, but i have no idea how to solve part A

2. position of the mass at any time t ...

$\vec{r} = 11\cos\left(\frac{\pi}{5}t\right) \, \vec{i} + 11\sin\left(\frac{\pi}{5}t\right) \, \vec{j}$

centripetal force ...

$\vec{F_c} = m\vec{a} = m \frac{d^2 \vec{r}}{dt^2}$