Speed is the rate of change of an object’s position per unit of time. It is also defined by the rate of motion, how fast an object is moving. The dimensions of distance divided by time calculate the speed, expressed in a formula v= d/t. The person who had gotten credit for being the first to measure speed by having in mind the distance covered for a period of time is the Italian Physicist and polymath Galileo Galilei.
The speed determined for a very short period of time, at a certain instant, is called instantaneous speed. The speedometer in cars and other vehicles is an instrument showing their instantaneous speed at any given moment.
As the motion of an object is covered, it often experiences changes of speed. The average speed is calculated by dividing the total distance traveled by the time of travel. It also represents the average of all instantaneous speeds.
Similarly to speed, the Velocity of an object is the rate of change of its position in regard to a set of criteria, thus change of position in a certain direction. In fact, Speed does not have a direction. Instantaneous velocity is the velocity of a moving object at a concrete point in time. To determine the average velocity one needs to consider the total displacement (or change in position with direction) of an object over the total period of time.
The ratio between any unit of distance to any unit of time equals a unit of speed. Here are some of the units which measure speed: meters per second, kilometers per hour, miles per hour, feet per second, knots (nautical miles per hour), mach (ration relative to the speed of sound).
The natural unit of speed is the speed of light in a vacuum which is a constant. Theoretically, nothing can travel faster than light.
|Centimeters per Second||Feet per Second||Kilometers per Hour||Knots||Mach||Meters per Second||Miles per Hour|
|1 Centimeter per Second =||1||0.0328||0.036||0.0194||3.0184 x 10-5||0.01||0.0224|
|1 Foot per Second =||30.48||1||1.0973||0.5925||0.00092001||0.3048||0.6818|
|1 Kilometer per Hour =||27.7778||0.9113||1||0.54||0.00083845||0.2778||0.6214|
|1 Knot =||51.4444||1.6878||1.852||1||0.001553||0.5144||1.1508|
|1 Mach =||33130||1087||1193||643.9957||1||331.3||741.097|
|1 Meter per Second =||100||3.2808||3.6||1.9438||0.003018||1||2.2369|
|1 Miles per Hour =||44.704||1.4667||1.6093||0.869||0.001349||0.447||1|