Velocity

            Velocity is the speed an object has in a particular direction.  For example, an airplane flying south at a speed of 300 km/h south has a velocity of 300 km/h south.  Velocity is expressed in distance over time with direction. 

            There is an important difference between speed and velocity.  Speed is the rate of motion, but it does not indicate anything about the direction of the motion.  When something is said to have a speed of 40 miles per hour, the direction is unknown.  To specify the velocity, it is necessary to indicate both the rate and motion.  For example, a body may have a velocity of 40 miles per hour toward the north.  Mathematically, velocity is a vector quantity, because it has both speed and direction. 

            Velocity may be uniform, which means the distances and the direction traveled during a given unit of time are the same throughout the motion.  To find the uniform velocity of a body, all you  need to do is divide the distance traveled by the time.  This can be put into a formula, v=d/t, where v= velocity, d= distance, and t= time.

            Velocity may be variable.  This means that the distances traveled in a given unit of time are not equal throughout the motion, or that the direction changes, or both.  For example, a moving object could have a velocity of 30 meters per second at a certain instant and then speed up to 60 meters per second.  If the object gained speed uniformly, it’s average velocity would equal it’s initial velocity plus it’s final velocity divided by two.  This can be written Av.  V= ( v-1+ v-2)/2 where Av. V represents the average velocity, v-1 is equal to the initial velocity and v=2 is equal to the final velocity.

By: Mandy Graham