Noah Formula is in an airplane which is flying at constant speed in a circular course of radius 6500 m, circling O’Hare‘s airplane prior to landing. Noah observed that the plane completes each round trip in 345 seconds (5 minutes & 45 seconds).
What is the speed of the airplane?
AND
What is the centripetal acceleration of the airplane?

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".