11) A glass plate has a thickness of 4.0 mm. A light beam is incident from air towards the glass plate at an angle of incidence of 60 °. How long does it take for the light beam to pass the glass plate? The refractive index of the glass is 1.55.

that would be because of both gravity and friction. so     c

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me

365.25 earth days are in the year of a light year

b

explanation: