physics
posted by john .
The earth orbits the sun once a year (3.16 107 s) in a nearly circular orbit radius 1.50 1011 m. With respect to the sun, determine the following.
(a) the angular speed of the earth
(b) the tangential speed of the earth
(c) the magnitude and direction of the earth's centripetal acceleration magnitude
direction
i solved for a and got 1.988E7 and for b got 2.98E4
but cant get c

centripetal acceleration= w^2*r
you found w in part a. r is given.