An optic fiber is made of clear plastic with index of refraction of 1.50. for what angle of incidence will light remain within the plastic "guide"?

Me plz i don’t know the charges on each of these

Explain why the aperture of the spherical mirror should be small compared to the radius of curvature of the mirror.

An airplane flies eastward and always accelerates at a constant rate. at one position along its path it has a velocity of 34.3 m/s, it then flies a further distance of 40100 m and afterwards its velocity is 47.5 m/s. find the airplane\'s acceleration and calculate how much time elapses while the airplane covers those 40100 m.