Average Speed and Average Velocity

Average Speed is the ration of distance per unit time.

• Speed is always positive.
• In the SI system, the unit of speed is the meter per second (m/s)
• In practice, the speed of automobiles, aircraft, and other everyday objects is ofteneasured in kilometers per hour (km/h):

Average Velocity is the ratio of the change of position and the time interval.

is also written as:

• In the SI system, the unit of speed is the meter per second (m/s)
•  Velocity can be positive or negative. A negative velocity refers to motion in the negative direction for the coordinate axis chosen.
• We cannot tell the velocity is positive or negative until the direction at the x-axis is specified.