interestingly even light (in a medium) can travel faster than the speed of light in that medium now both speeds will be slower than the speed of light in vaccu

interestingly even light (in a medium) can travel faster than the speed of light in that medium now both speeds will be slower than the speed of light in vaccum (as that is the highest speed that can be attained) as the light "slows" down from faster speed to its normal speed radiation is emitted https://en.wikipedia.org/wiki/Cherenkov_radiation https://en.wikipedia.org/wiki/Cherenkov_radiation