Why do airplanes need to be pressurized for passenger safety when flying high in the atmosphere?

a high pressure system is a dense air mass that is usually cooler and drier than the surrounding air. a low pressure system is a less dense air mass that is usually wetter and warmer than the surrounding air.

in general, areas that experience high atmospheric pressure also experience fair weather. low pressure systems can cause the formation of clouds and storms. air usually flows from areas of high pressure to areas of low pressure..

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s