Aboat is headed with a velocity of 18 meters/second toward the west with respect to the water in a river. if the river is flowing with a velocity of 2.5 meters/second in the same direction as the boat. what would be the magnitude of the boat's velocity? a. 16.5 meters/second b. 20.5 meters/second c. 18 meters/second d. 2 meters/second e. 45 meters/second

B

Explanation:

The boat's velocity relative to the earth = the boat's velocity relative to the river + the river's velocity relative to the earth

v = 18 m/s + 2.5 m/s

v = 20.5 m/s

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.