9. A car runs out of fuel at the top of hill A. The driver hopes...

  

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9. A car runs out of fuel at the top of hill A. The driver hopes to get to the service station by letting the car roll downhill with its engine switched off. There is a small hill, B, in between as shown. The distance from hill A to hill B along the road is 0.2 km and from hill B to the service station is 0.4 km. Hill A 50.0 m -~- 0.27 Hill B 30.0 m Service Station The top of hill A is 50.0 m above the service station and the top of hill B is 30.0 m above the service station. (a) When the car reaches hill B its speed is 5.0 ms. Assuming that the car starts from rest at hill A, show that the average frictional force acting on the car is 750 N. The mass of the car is 800 kg. [5] (b) Assuming that the frictional force remains constant throughout, determine whether or not the car reaches the service station. F... E.k. t. W... mg hq. fmx. t. fg. mg.hz. F= 5.7.5.N. A 2 It will reach the station, because it need and the P is greater SASN (c) Besides friction in the wheels and tyres, name another source of frictional resistance for the moving car, and explain why it will not in fact remain constant during the motion. [3] [2] 9. A car runs out of fuel at the top of hill A. The driver hopes to get to the service station by letting the car roll downhill with its engine switched off. There is a small hill, B, in between as shown. The distance from hill A to hill B along the road is 0.2 km and from hill B to the service station is 0.4 km. Hill A 50.0 m -~- 0.27 Hill B 30.0 m Service Station The top of hill A is 50.0 m above the service station and the top of hill B is 30.0 m above the service station. (a) When the car reaches hill B its speed is 5.0 ms. Assuming that the car starts from rest at hill A, show that the average frictional force acting on the car is 750 N. The mass of the car is 800 kg. [5] (b) Assuming that the frictional force remains constant throughout, determine whether or not the car reaches the service station. F... E.k. t. W... mg hq. fmx. t. fg. mg.hz. F= 5.7.5.N. A 2 It will reach the station, because it need and the P is greater SASN (c) Besides friction in the wheels and tyres, name another source of frictional resistance for the moving car, and explain why it will not in fact remain constant during the motion. [3] [2]