[填空题]
One possibility for a low-polluti23ui wb+ku 6zaon automobile:c0qz64ov sqhuc(( vmn +*iby is for it to use energy stored in a heavy rotating flywheel. Suppose such a car has a total mass of 1400 kg, uses a uniform cylindrical flywheeqbc0m6uy q (hcv+ *s:(n iz4vol of diameter 1.50 m and mass 240 kg, and should be able to travel 350 km without needing a flywheel “spinup.” (a) Make reasonable assumptions (average frictional retarding force = 450N twenty acceleration periods from rest to equal uphill and downhill, and that energy can be put back into the flywheel as the car goes downhill), and show that the total energy needed to be stored in the flywheel is about $ 1.7\times10^{8 }$J. $ \times10^{ 8}$ J (b) What is the angular velocity of the flywheel when it has a full “energy charge”? $rad/s$ (c) About how long would it take a 150-hp motor to give the flywheel a full energy charge before a trip? $\approx$ min