The optical path of a monochromatic light is the same if it goes through 4m of glass or 4.5m of a liquid. If the refractive index of glass is 1.5, what is the refractive index of the liquid? Pls answer this I will mark you as the brainiest.

15.3 cos 65 degrees trig

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

conservation of mass

mass before something happens = mass afterwards