Which atmospheric layer has around 80 percent of the mass of the earths armosphere?

If you add 10ml of hot water to 10ml of cold water and the change in tempature 8°c calculate how much energy is gained by the cold water

Aroller coaster is traveling at 13 mi./s when you purchase a hill that is 400 m long and down the hill exonerate at 4.0 m/s squared what is the final velocity of the posterior found your answer to the nearest number

What is the wavelength of a wave with a velocity of 50 m/s and a frequency of 5hz a 250 m b 0.1 m c 10m d 0.01 m