I am studying the material in Chapter 74, but the questions require the use of HCM, which I do not currently have, so I am not able to post questions, since I’m am unsure I will be able to answer them.
For Chapter 75 though – I present these 2:
1. Two cars are moving at 50 mph in the same directions in the same lane. The cars are separated by 20 ft per 10 mph. The coefficient of friction (skidding) is 0.65. The reaction time is assumed to be 0.4 sec.
a) If the lead car hits a parked car, what is the speed of the second car when it hits the first car?
b) If the lead car hits a parked car and comes to an abrupt halt, at what speed does the rule of 1 car length (20 ft) per 10 mph of speed become unsafe?
c) At 60 mph what should the rule actually be?
2. Two vehicles collide head on while traveling a curve with a 4% grade. Vehicle A skidded 200 feet downhill before colliding with vehicle B. Vehcile B skidded 150 ft. The police report estimates both car traveling at 30 mph prior to the collision. Assume a coefficient of friction of 0.5.
a) What was the speed of vehicle A prior to hitting the brakes?
b) What was the speed of vehicle B prior to hitting the brakes?
c) Which assumption produces the greatest possible error?
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