v = d/t
d is (usually) measured in metres, but can also be measured in other units such as km, cm and mm
t is (usually) measured in seconds, but can also be measured in other units such as minutes and hours
Therefore, v is usually stated in metres per second (m s-1). However, when other units are used for distance and time, we can have other units such as km hr-1.
NOTE #11 km hr-1 = 0.277 m s-1
1 m s-1 = 3.6 km hr-1
This equation only works for uniform motion (constant speed or stopped).
Speed can be calculated from a d-t graph by finding the gradient (rise/run).