Everything is made up of elements Modern elements are less evocative but more numerous, they make up just over one hundred basic substances All things consist of particles called atoms The way molecules behave governs the workings of many machines, such as ships, airplanes, pumps, refrigerators, and combustion engines. Molecules of gases are so hyperactive that they will fill any space open to them In liquids, the molecules are less energetic and go haphazardly around …showed first 75 words of 770 total…

…showed last 75 words of 770 total…to force the aircraft forward By using the downward thrust of its jet engine, the jump jet can dispense with the need for a runway and take-off vertically from the ground An airfoil works better in water, which is denser than air and therefore gives more lift at lower speed Frees from friction with the water, a hydrofoil can skim over the waves at two or three times the speed of the fastest floating boats