The speed s of blood that is r centimeters from the center of an artery is given below, where c is a constant, r is the radius of the artery, and s is measured in centimeters per second. suppose a drug is administered and the artery begins to dilate at a rate of dr/dt. at a constant distance r, find the rate at which s changes with respect to t for c = 1.54 105, r = 1.3 10-2, and dr/dt = 1.0 10-5.

s = c(r^2 − r^2)

ds/dt =/s

a skateboard rolling across the street - apex

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.