Map of driving directions from Spring, TX to Houston, TX. Click here to show map. Drag the line on the map to calculate the driving distance for a different route. If you want to verify these driving directions or look for another possible route, you can try. Google Maps, Bing Maps, or MapQuest.
The second (symbol: s) (abbreviated s or sec) is the base unit of time in the International System of Units (SI).
The first principle simply says that the laws of physics apply equally to everyone in all situations. The second principle is the more important one. It stipulates that the speed of light in a vacuum is constant.