At t = 0, an automobile traveling north begins to take a turn. It follows one-quarter of the arc of the circle of radius 9.8 m until, at t = 1.38 sec, it is traveling east. The car does not alter its speed during the turn.

Answer 1

and then what? runs out of gas? breaks an axle? gets hit by a semi?

Now, if you want the car's speed during the turn, that would be

pi/2 * 9.8 m/1.38s = 11.2 m/s