Neglect the diameters of the small pulleys and establish the relationship between the velocity of A and the velocity of B for a given value of y. If b = 1.17 m, y = 0.63 m, and vA = 1.90 m/s downward, what is the velocity of B (positive if downward, negative if upward).

i'm thinking more like energy

a and b sometimes have a positive value

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.