I need some help with a problem our professor handed out. Thanks in advance for any help. A car is undergoing circular motion with a radius of 200m. Its initial speed is 3.00 m/s. The car moves so that its tangential acceleration is equal to its centripetal acceleration at all times. Calculate (a) its speed and (b) its centripetal acceleration 40.0 s later. (c) At what instant will the car's centripetal acceleration be equal to 9.80 m/s^2? (d) What will be its speed at that time. The A sub t, and A sub c keeps tripping me up.