Speed is the rate of change of distance with respect to time. The symbol for speed is V and the base units for speed in the metric system is [m/s]
Velocity is the vector "equivalent" of speed. The velocity of a moving object is the speed the object travels in one particular direction.
The symbol for velocity is .
Example To indicate the velocity of a transport truck going at a speed of 100 km/h to Montreal (in an easterly direction) you would write
= 100 km/h [E] ---> this is the velocity of the truck!
To calculate the average speed (or average velocity) of an object we use the general equation
If you are walking with your dog in the park at 30 cm/s. How far will you have traveled in 20 minutes?
[tip: don't forget to change units from cm/s to m/s and minutes into seconds]
[tip: when you're asked to find "how far" it means ... "find the distance"]
Given: vav = 30 cm/s = 0.30 m/s
t tot = 20 min = 20 min X 60 s/min = 1200 s
Find: dtot --> use the above equation for vav but rearrange it so that you can solve for dtot
dtot = 0.30 m/s X 1200 s = 360 m
Therefore you and the dog would have walked a total distance of 360 m