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\%