A ball rolls down a roof that makes an angle of 30.0 degrees to the horizontal. It rolls off the edge of the roof with a speed of 5.00 meters per second. The distance straight down to the ground from the edge of the roof is 7.00 meters. a) How long is the ball in the air

0.97s

Explanation:

First of all solving the second equation of motion in the vertical direction we have

Vy= Vosinစ

= 5m x sin 30= 2.5m/s

So solving for t time in second equation of motion we will have

t= - Vy +or- √(Vy²- 4{g/2)- h)/ (2g/2)

Substituting 7m for h

We have

t = -2.5+or- √ 2.5²-4(4.9)-7/9.3

We have

t= 0.97s as the positive rational answer

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.