A string is wrapped multiple times around a massive pulley of radius 0.3 meters. A mass is attached at the free end of the string, as shown in the image above. The mass is released at t=0 seconds. Assume friction in the pulley is negligible. This pulley has a moment of inertia of 59 kg·m2. Immediately after t=0, the tension in the rope is 22 newtons. What will be the angular velocity of the pulley after 4 seconds?

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.