Question

Two vehicles collided head on while traveling on a curve tangent with a 3% grade. Vehicle V1 skidded 195 feet downhill before colliding with vehicle V2. Vehicle V2 skidded 130 feet. The police report estimates that the speed of both vehicles at impact was 25 mph, based on vehicle deformation. Assume a coefficient of friction of 0.48. What is V1 speed at the beginning of the skid?

Answer 1

Answer:

Speed V1 at the beginning of the skid  = 57.075 mph

Explanation:

Calculate the V1 speed at the beginning of the skid

V1 ( speed before brake was applied ) = ?

distance travelled by Vehicle 1 = 195 ft

curve tangent for vehicle 1 =  - 3% = - 0.03

coefficient of friction = 0.48

speed at Impact = 25 mph

To determine the V1 speed at the beginning of the skid we have to apply AASTHO

d1 = $( \frac{VA^{2} - VA^{12} }{30(F+N)} )$

195 =  $(\frac{VA^2- 25^2}{30(0.48-0.03)} )$

Hence : VA = 57.075 mph