A 1000kg car is traveling 10m/s to right when it collided head- on with a 2000kg pickup truck traveling 9m/s to the left. An 85kg linebacker is traveling 8m/s to the right when it collided head-on with a 75 kg running back traveling 11 m/s to the left

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

total distance/total time

(85 + 82)/(5+3)

167/8

20 just over