Speeding up and slowing down A 1400kg car, starting from rest, accelerates to a speed of...

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Speeding up and slowing down A 1400kg car, starting from rest, accelerates to a speed of 30mph in 10 seconds. a) What is the force on the car (assumed constant) over this period of time? b) Where does this force come from? That is, what is the external agent that exerts this force on the car, and what is the nature of this force? c) Draw a free-body diagram for the car. Indicate the direction of motion, and the direction of the acceleration. d) Now assume that the driver, traveling at 30mph, sees a red light ahead and pushes on the brake pedal. Assume that the coefficient of static friction between the tires and the road is s = 0.7, and that the wheels don't "lock": that is to say, they continue rolling without slipping on the road as they slow down. What is the car's minimum stopping distance? e) Draw a free-body diagram of the car for the situation in (d). Again indicate the direction of motion, and the direction of the acceleration. (f) Now assume that the driver again wants to stop as in part (c), but he presses on the brakes too hard, so the wheels lock, and, moreover, the road is wet, and the coefficient of kinetic friction is only k: = 0.2. What is the distance the car travels now before coming to stop? Speeding up and slowing down A 1400kg car, starting from rest, accelerates to a speed of 30mph in 10 seconds. a) What is the force on the car (assumed constant) over this period of time? b) Where does this force come from? That is, what is the external agent that exerts this force on the car, and what is the nature of this force? c) Draw a free-body diagram for the car. Indicate the direction of motion, and the direction of the acceleration. d) Now assume that the driver, traveling at 30mph, sees a red light ahead and pushes on the brake pedal. Assume that the coefficient of static friction between the tires and the road is s = 0.7, and that the wheels don't "lock": that is to say, they continue rolling without slipping on the road as they slow down. What is the car's minimum stopping distance? e) Draw a free-body diagram of the car for the situation in (d). Again indicate the direction of motion, and the direction of the acceleration. (f) Now assume that the driver again wants to stop as in part (c), but he presses on the brakes too hard, so the wheels lock, and, moreover, the road is wet, and the coefficient of kinetic friction is only k: = 0.2. What is the distance the car travels now before coming to stop?