10. 11. 12. 13. 14. Ice skaters often end their performances with spin turns, where they spin very fast about their center of mass with their arms folded in and legs together. Upon ending, their arms extend outward, proclaiming their finish. Not quite as noticeably, one leg goes out as well. Suppose that the moment of inertia of a skater with arms out and one leg extended is 3.2 kg mzand for arms and legs in is 0.80 kg m2. If she starts out spinning at 5.0 rev/s, A} what is her angular speed when her arms and one leg open outward? B) Was rotational kinetic energy conserved in this process? At what speed does a 1000 kg compact car have the same kinetic energy as a 20,000 kg truck going 25 km/h? The turntable in a microwave oven has a moment of inertia of 0.040 kg m2 and rotates continuously, making a complete revolution every 4.0 s. What is its rotational kinetic energy? A 20 kg child is on a swing that hangs from 3.0mlong chains, as shown below. What is her speed vi at the bottom ofthe arc if she swings out to a 45 angle before reversing direction? A roller coaster starts from rest at its highest point and then descends on its {frictionless} track. Its speed is 30 m/s when it reaches ground level. What was its speed when its height was half that of its starting point? A. 11 m/s B. 15 m/s C. 21 m/s D. 25 m/s A block slides down a smooth ramp, starting from rest at a height h. When it reaches the bottom it's moving at speed v. It then continues to slide up a second smooth ramp. At what height is its speed equal to v/2? Fleas have remarkable jumping ability. A 0.50 mg flea, jumping straight up, would reach a height of 40 cm ifthere were no air resistance. A. What would be the initial kinetic energy as the flee leaves the ground? B. if when adding air resistance, the jump that the flee can achieve is only 20 cm, how much energy was lost due to the work done by the air resistance