How does an oxygen concentrator machine work?

Is it true that any marking on an angle means that the angle measure 90 degrees?

A billiard ball strikes and rebounds from the cushion of a pool table perpendicularly. the mass of the ball is 0.38 kg. the ball approaches the cushion with a velocity of + 2.50 m/s and rebounds with a velocity of - 1.90 m/s.

Dan is gliding on his skateboard at 4.00 m/s. He suddenly jumps backward off the skateboard, kicking the skateboard forward at 8.00 m/s. Dan's mass is 50.0 kg and the skateboard's mass is 7.00 kg.

An electron is ejected at a speed of 1.7*10^6 m/s from the electron gun of a computer monitor. If the viewing screen is 32 cm from the end of the gun, how far will the electron travel in the vertical direction before hitting the screen?

List three examples each of objects that are commonly measured by mass by volume and by length

A scientist has been tracking and studying a population of deer in Yellowstone National Park. He surveys the population every six months. Usually, the population is thriving and has a gene pool with a wide variety of traits.

How long will it take a bike traveling at 5 meters per second to travel 25 meters south? A. 5 s B. 0.2 s C. 5 s south D. 0.2 s south

Two masses are connected by a string which passes over a pulley with negligible mass and friction. One mass hangs vertically and one mass slides on a frictionless 30.0-degree incline. The vertically hanging mass is 6.

The coordinates 40 degrees north and 100 degrees east falls in what country?

Which type of radio waves have the highest frequency and are used in radar detection? microwaves x-rays waves infrared waves gamma waves