posted by physics .
i have a question in my book
centripetal acceleration = r^-1 v^2
ok I agree
but in my book acceelration is labeled as a vector but yet the velocity is not...
By v it means the component of the V vector that is tangent to the circle of radius r.
It identifies the centripetal acceleration as an inward pointing vector because the author wants to make sure you know that centripetal acceleration has a direction, namely toward the center.