A student drops a rock from a bridge to the water 13.1 m below.
With what speed does the rock strike
the water? The acceleration of gravity is
9.8 m/s squared

Answer in units of m/s.

let us use the expression v = ./2gS in both the cases.

a) In the first case g = 9.8 m/s^2 and S = 10.3 m.

So v = 14.21 m/s

b) in the second case, g = 1.64 m/s^2 and S = 4.2 m = 3.71 m/s

00

Explanation:

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.