Awarding 10 points An object is projected with a velocity of 20m/s making an angle of 45 with the horizontal. The trajectory equation is h=Ax-Bxsquare where h is height, x is horizontal distance . A and B are constants . The ratio A and B is (g=10m/s)

so easy. just google the electromagnetic waves and it’ll pop up.

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.

the answer is 12 as i may remember

: )