correct as I see it.
A body of mass 5 kg moves in a counterclockwise circular path of radius 10 meters in the xy-plane, making one revolution every 7 seconds. At the time t=0, the body is at the rightmost point of the circle.
r(t)= 10cos(2pi(t)/7i+10sin(2pi(t)/7
Now my a(t)=r''(t) vector comes out to be:
-40pi^2/49cos(2pi(t)/7)i-40pi^2/49sin(2pi(t)/7)
Is this right?