Three kids are riding on a snow sled traveling horizontally without friction at 19.8 m/s. The masses of Kid A, B, and C are 42.8 kg, 31.5 kg, and 25.9 kg, respectively.

What is the new velocity of the sled if Kid A jumps off vertically from the sled? (Kid A velocity = 0)

Explanation:

Momentum is conserved:

m₁v₁ = m₂v₂

(42.8 kg + 31.5 kg + 25.9 kg) (19.8 m/s) = (31.5 kg + 25.9 kg) v

v = 34.6 m/s

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.