Mathematical Facts

  1. The weight of one cu. ft water = $$62.425{\text{ }}lb$$
  2. The velocity of light in a vacuum $$ = 2.99776 \times {10^8}m/\sec = 186,284\,{\text{miles/sec}}$$
  3. The velocity of sound in dry air at $$0^\circ C = 33,136\,{\text{cm}}/\sec = 1,087\,{\text{ft}}/\sec $$
  4. The mean radius of Earth $$ = 3,959{\text{ }}miles$$$$ = 6,371{\text{ }}km$$
  5. An electronic charge $$ = 5 \times {10^{ – 19}}{\text{ }}e.s.u$$
  6. The mass of an electron $$ = – 9.1 \times {10^{ – 28}}{\text{ }}gm$$
  7. The polar diameter of the Earth $$ = 7900{\text{ }}miles$$
  8. The Equatorial diameter of the Earth $$ = 7926{\text{ }}miles$$
  9. The circumference of the Earth $$ = 25000{\text{ }}miles$$
  10. The total area of the Earth $$ = 197{\text{ }}million{\text{ }}sq{\text{ }}miles$$
  11. The total water area $$ = 71\% $$
  12. The total land area $$ = 29\% $$