Plz help me with this pe stuff

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?

An important dimensionless parameter concerned with very high-speed flow is the mach number, defined as v/c, where v is the speed of the object such as an airplane or projectile, and c is the speed of sound in the fluid surrounding the object. for a projectile traveling at 1170 mph through air at 50 ˚f and standard atmospheric pressure, what is the value of the mach number?

As seen in a us weather map, the h (or high) and l (or low) symbols indicate regions where surface air pressures are high or low, respectively, compared to surrounding areas. an h is plotted where the air pressure is highest and an l is plotted where the air pressure is lowest. proceeding outward and away from the center of a high pressure system, the air pressure "