A 400 kg train car moving at 10 m/s slams into a second train car with a mass of 200 kg at rest. The two train cars stay attached and continue rolling down the track. What is the velocity of
the train cars after the collision?

the earths atmosphere is made up of nitrogen and oxygen. solids can turn into gasses through a process called sublimation. sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase.

hope this : d

snell's law

refractve index = sin incidence / sin refraction