Disregarding air resistance, what is the speed of a ball dropped from 12 feet just before it hits the ground? (use 1 ft = 0.30 m, and use g = 9.8 m/s2.) 2.4 m/s 8.4 m/s 10.8 m/s 15.3 m/s

Speed of the ball, v = 8.4 m/s

Explanation:

In this question, we have to find the speed of a ball dropped from 12 feet just before it hits the ground.

We know that,

1 ft = 0.30 m

So, 12 ft = 3.6 m

Initial velocity of the ball, u = 0

Using third equation of motion and replacing a with g (it is a case of free fall)

v = 8.4 m/s

Hence, the speed of ball when it is dropped is 8.4 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.