*A pilot performs a vertical maneuver around a circle with a radius R. When the airplane is at the lowest point of the circle the pilot's apparent weight is 6 mg.
What is the acceleration of the plane at the lowest point?

Suppose a wheel with a tire mounted on it is rotating at the constant rate of 2.15 times a second. a tack is stuck in the tire at a distance of 0.373 m from the rotation axis. noting that for every rotation the tack travels one circumference (a) find the tack's tangential speed. (b) what is the tacks radial acceleration?