The fact that the galaxies are rotating at about the same velocity from the center to the edge as opposed to faster near the centers is evidence that .. a. there must be more gravity than that calculated from normal Mass
b. they are rotating slower over time
c. dark energy is pulling on them
d. they are measuring the velocities incorrectly ​

Why is there friction between objects

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?

Who was the first scientist to measure speed as distance over time?