Given the speeds of each runner below, determine who runs the fastest.

emily runs 15 feet per second.
jake runs 109 feet in 8 seconds.
stephanie runs 1 mile in 467 seconds.
tony runs 760 feet in 1 minute.

a. emily
b. jake
c. stephanie
d. tony

option A

Explanation:

we will converts all the velocity into SI unit then we can tell who is running fast.

a) Emily runs at 15 ft/s

1 ft/s = 0.3048 m/s

15 ft/s = 4.572 m/s

b) Jack runs at 109 ft in 8 s

1 ft = 0.3048 m

109 ft = 33.22 m

speed = 33.22/8 = 4.152 m/s

c) Stephanie runs 1 mile in 467 seconds

   1 mile = 1609.34 m

  speed = 1609.34/467

      v = 3.45 m/s

d) Tony runs 760 feet in 1 minute.

1 ft = 0.3048 m

760 ft = 231.65 m

speed = 231.65/60 = 3.86 m/s

from the above solution Emily runs fastest.

the correct answer is option A

answer: decibel

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.