The train A is traveling at a constant velocity of 120 km/hr. The car B is traveling at 90 km/hr. At the instant the driver of the car notices the train, the driver slows down at a rate of 3m/s2. Find the velocity and acceleration of the train relative to the car.

the independent variable, or the one that is intentionally manipulated is the speed.

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.

b. a lightning bug, plug of grass, and a worm