A535 kg roller coaster car began at rest at the top of a 93.0 m hill. now it is at the top of the first loop-de-loop. this roller coaster’s track is nearly frictionless, so resistance can be ignored. using g = 9.8 m/s2, what best describes the roller coaster car when it is at the top of the loop-de-loop? the car has only potential energy, so it is moving at 0 m/s. the car has both potential and kinetic energy, and it is moving at 24.6 m/s. the car has both potential and kinetic energy, and it is moving at 34.9 m/s. the car’s potential energy has all been converted to kinetic energy, so it moves at 42.7 m/s.

as technology advances, new experiments often expose problems in accepted theories. c

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-lavira: )

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.