Many head-on collisions occur on two-lane roads when passing because

misjudge the closure rate of oncoming traffic

Explanation:

Many head-on collisions occur on two-lane roads when passing because drivers misjudge the closure rate of oncoming traffic. Some drivers tends to miscalculate the speed and closure rate of oncoming traffic thereby taking decision that leads to collisions and accidents. Drivers should always account for safety and effectively estimate closure rate of oncoming traffic before passing or squeezing in front of them.

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.