In everyday use and in kinematics, the speed of an object is the magnitude of the rate of change of its position with time or the magnitude of the change of its position per unit of time; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero. Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second, but the most common unit of speed in everyday usage is the kilometre per hour or, in the US and the UK, miles per hour. For air and marine travel the knot is commonly used. The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in a vacuum c = 299792458 metres per second.
| Common symbols | v |
| SI unit | m/s, m s −1 |
| SI dimension | L T −1 |
關於Speed
Jack is a young police officer who, with the help of a passenger Annie, must get the people off the bus that has to maintain above 50 mph or a bomb in the bus will explode.
Speed的成就
The film won two Academy Awards. The movie is the first in the series.
您不知道JSpeed的熱門事實
Velocity.. Temporal rates.
