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4. A car moving at 8 m/s takes a circular turn with a radius of 24 m. If the net force acting upon the car is 3500 N, what is the mass of the car? 6. While riding on a roller coaster, a 64-kg boy experiences a net force of 900 N at the top of a circular loop with a radius of 10 meters. What is the boy's speed? Round to two decimal places. 8. An electron (m = 9.11x10-31kg) travels in a circle with a radius of 0.003 meters. What is the speed of the electron in m/s if the force acting on it is 5.2x10-14 N