A rock is thrown downward from the top of a cliff If the rock hits the ground after 2.0 s, with a velocity of 12 m/s what is the height of the cliff?

Explanation:

v = u + a t

12 = 0 + 2a

a= 12/2

a=6 m/s2

v^2 - u ^2 = 2 as

12 ^2 - 0 ^2 = 2 * 6 * s

144 = 12 s

s = 144/12

s = 12 m

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.