During instruction on parachuting, rookies are told to flex their knees while landing. Determine the force of impact on an 80. kg parachutist falling at a terminal velocity of 10
m/s who flexes her knees and takes 0.80 s to land. Consider the case where the rookie
does not flex his legs, and stops in 0.050 s. How much force is applied in this case?

correct it is c.) b b

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.