1. If the Braking Foree Ration (BFR) value of a car is 5, then what is the ratio
ID: 1712322 • Letter: 1
Question
1. If the Braking Foree Ration (BFR) value of a car is 5, then what is the ratio of percentage of the force allocated to the rear brakes to that of percentage of the force allocated to front brakes A) 0.02 B) S C)0.2 D) 0.05 2. A truck travelling at 75 mih has a braking efficiency of 70 %. The coefficient of road adhesion is 0.so. Ignoring the acrodynamic resistance determine the theoretical stopping distance on a level ground. A) 340.9 f B) 345.6 ft C) 425.6 ft D) 338.6 t 3. A 100 ft equal tangent vertical curve is represented by following equation. Identify respective initial and final grades of the curve y=10x2-6x + 200 A) 6%,6% B)-65.18% C)-6% ,6% D)-18% ,-6%Explanation / Answer
Q(1) Ans (C)
Braking force ratio = B1/B2 = 5
means front wheels braking force is 5 times greater than the rear wheel force, so ratio of the percentage of rear force to front = B2/B1 = 1/5 = 0.2
Q.2 Simply take the standard value of the driver reaction time from whatever standards you follow, and then apply the formula , s = ut+0.5 at^2
Where a = deceleration = 0.7*0.8 , u = initial velocity = 75 mi/hr = 110 ft/sec
Q.3 The equation of curve is given by
y = ax2 + bx + c
where a = (g2-g1)/2L
and b = g1, so g1 = -6%
so, (g2 +6)/200 = 10, this does not make sense, because g2 is coming to be a huge . There is a mistake in the problem, value of a must be very small.
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