Which discovery by astronomer Vera Rubin helped prove the existence of dark matter?Which statement accurately describes the Doppler effect?

The friction red blood cells encounter when moving past each other. cardiac output: the amount of friction blood encounters during flow through blood vessels. blood pressure: the force of the blood against the vessel wall. blood viscosity: the volume of blood pumped out by one ventricle each minute.

Atypical human cell is approximately 12.00 μm in diameter and enclosed by a membrane that is 5.000 nm thick. (a) what is the volume of the cell including the membrane? (b) what is the volume of the cell membrane? (c) what percent of the total volume does its membrane occupy? to simplify the calculations, model the cell as a sphere. enter your answers using four significant figures.

During the winter, this species of fox has white fur, but in the summer, it has brown fur. what environmental change may have lead to this fox's fur color? snow cover increase in sun's brightness volcanic eruption global warming