A girl is sitting in a sled sliding horizontally along some snow (there is friction present).

The normal force supporting the girl and sled is 636 N.

If the coefficient of static friction is 0.38, and the coefficient of kinetic friction between snow and sled is 0.25, what is the force of friction exerted on the sled?

Alinearly polarized electromagnetic wave has an average intensity of 196 w/m^2. this wave is directed towards two ideal polarizers (in real polarizers, transmission is also effected by reflection and absorption). polarizer a is oriented with its transmission axis at an angle of θ_1=20.8∘ with the incident electric field. polarizer b has its axis at an angle of θ_2=63.0∘ with the incident electric field. what is the average intensity of the wave after it passes through polarizer a? what is the average intensity of the wave after it passes through polarizer b? suppose that the two polarizers a and b are interchanged. what would the average intensity be after passing through both polarizers?