Find the rate of positive acceleration of an automobile which went from a complete stop to a velocity of 30 meters per second in 10 seconds

Which statement is true about an object that is moving in a circular motion due to centripetal force, f, when the radius of its circular motion is doubled? the new force then becomes equal to 2f the new force then becomes equal to f the new force then becomes equal to f/2 the new force then becomes equal to f2 the new force then becomes equal to 1/f