Many man-made substances are replacing certain natural materials because either the quantity of the natural products can’t meet our ever-increasing requirement, or more often, because the physical properties of the synthetic substances, which is the common name for man-made materials, have been chosen, and emphasized so that it would be of the great use in the field which it is to be applied. 2.Various machine parts can be washed very clean and will be as clean as new ones when they are treated by ultrasonics, no matter how dirty and irregularly shaped they may be. 3.The super-cooling effects of the cryogenics which convert liquid helium and other gases into “superfluids” and metals into “superconductors”, making them non-resistant to electricity, could change the world in a number of ways. 4.The slow development of IRBMs and ICBMs in the United States was the result of low military budgets resulting from a feeling of a superiority that emerged after World War II, when the United States alone had the atomic bomb(a feeling that disappeared in 1949 when the Soviet Union exploded its first nuclear weapon) and the larger number of technical problems, especially in the area of terminal guidance, that plagued ballistic missiles far more than winged missiles.