What does the troposphere protect us from?

What is created when solids,liquids,an gases mix with one another

Aman throws a football straight into the air. as it rises, it slows down. which type of energy is the football gaining?

Determine the fraction of the magnitude of kinetic energy lost by a neutron (m1 = 1.01 u) when it collides head-on and elastically with a target particle at rest which is 21h (heavy hydrogen, m = 2.01 u).