Only 3% of the water on earth is usable by humans. even though that 3% is through the water cycle, we still need to be careful not to waste water.

Moon effect. some people believe that the moon controls their activities. if the moon moves from being directly on the opposite side of earth from you to being directly overhead, by what percentage does (a) the moon's gravitational pull on you increase and (b) your weight (as measured on a scale) decrease? assume that the earth–moon (center-to-center) distance is 3.82 × 10^8 m, earth's radius is 6.37 × 10^6 m, moon's mass is 7.36 × 10^22 kg, and earth's mass is 5.98 × 10^24 kg.

Positrons are spontaneously emitted from the nuclei of

What is the freezing point of radiator fluid that is 50% antifreeze by mass? kf for water is 1.86 ∘c/m.