Concept Simulation 5.1 reviews the concepts that are involved in this problem. A child is twirling a 0.0138kg ball on a string in a horizontal circle whose radius is 0.0936 m. The ball travels once around the circle in 0.550 s. (a) Determine the centripetal force acting on the ball. (b) If the speed is doubled, by what factor does the centripetal force increase? (a) Number .169 Units (b) Number 4 Units