Question
Write your answers (with 3 significant figures)in the blanks provided. 1. A 2000 lbs car is driving down a 10 degree slope at 40 mph. The coefficient of dynamic friction between the road and the tires is 1, and the driver hits the brakes. Full 30 points will be awarded for the correct answer to the following question: What is the cars stopping distance? If the full credit cannot be awarded, then partial credit will be awarded for the correct answers to the following questions i) What is the initial velocity of the car in SI units? ii) What is the mass of the car SI units? iii) What is the weight of the car in SI units? iv) What is the component of cars weight perpendicular to the surface? y) What is the component of the car's weight parallel to the surface? vi) What is the magnitude of the Normal force acting on the car? vii) What are the magnitude and direction of the force of friction between the car and the road? viii) What is the total force acting on the car parallel to the surface? ix) What is the magnitude and direction of the car's acceleration?.. x) How far will the car travel before it stops?
Explanation / Answer
i) 17.8816 m/s
ii) m = 907.18 kg
iii) W = 8890.364 N
iv) W*cos10 = 8755.3 N
v) W*sin10 = 1543.8 N
vi) N = W*cos10 = 8755.3 N
Vii) f = u*N = 8755.3 N up the plane
viii) fnet = w*sin10 - f = -7211.5 N
ix)a = Fnet/m = -7.95 m/s^2
x) s = v^2/2a = 20.11 m
