What is the refractive index of a medium?

Atrain departs from its station at a constant acceleration of 5 m/s. what is the speed of the train at the end of 20s?

An initially unpolarized light if intensity 500 w/m^2 passes through four polarizers. the transmission axis between adjacent polarizers is 45∘. what percentage of the initial intensity is transmitted by the system?

True or false graphs must include scales that increase by the same amount