m 4. Joel has tied a 0.25 kg stone to the end of a 0.85 m rope. As he spins the rock above his head, Joel exerts a 45.5 N centripetal force to keep the stone in circular motion. Based on this information, what is the period, T, of the stone's circular motion. 0 0.67 s m 5. The moon of a certain planet is observed to have a nearly circular orbit of radius 3.89 at 105 km, and an orbital period of 25.4 days. What is the mass of the planet? 0 4.65 k 1025 kg 0 4.39 k 1025 kg 0 7.23 k 1024 kg 0 2.32 k 102'1 kg m 8. A 0.017 kilogram pebble is stuck in a car tire's tread. The radius of the tire is 0.38 m, and it completes a rotation every 0.23 seconds. What is the centripetal force that the tire tread is exerting on the pebble? Q 1.8M m 9. A communications satellite orbits around Earth. Earth has a radius of 6380 km, and the satellite orbits 1140 km above Earth's surface. The satellite has a mass of 915 kg, and moves with a velocity:r of 7280 mfs. Based on this information, what is the centripetal force exerted on the satellite