This problemn contains more information than necessary to answer the question. It may be they are trying to confuse you. Or uou may need the extra information in a followup question about whether you hit the car or not.
The deceleration of the car in front has nothing to do with your car or reaction time. It is
a = -F/m,
where F is the friction force and m is the mass. The minus sign indicates deceleration.
Although they do not tell you the mass, it will cancel out of the equation when you write
F = 0.92 m g
Thus a = -0.92 g
You are driving at the speed of 33.4 m/s
(74.7296 mph) when suddenly the car in
front of you (previously traveling at the same speed) brakes. Considering an average human reaction, you press your brakes 0.484 s later. Assume that the brakes on both cars are fully
engaged and that the coefficient of friction is 0.92 between both cars and the road. The acceleration of gravity is 9.8 m/s2 . Calculate the acceleration of the car in front
of you when it brakes.
1 answer
1 answer