Section 1: Describing Motion

SpeedSpeed is how far you travel over a period of

time.Speed is expressed in the formula s=d/t

(speed = distance/time).

If you walk 20 meters over 10 seconds, this formula would show that you have a speed of 2 m/s.

Average speedAverage speed is used to calculate the speed

traveled over a total distance in a certain time.

If you drive 360 miles to Florida over 6 hours time, the formula s(average) = d(total)/t(total) will calculate that you have traveled at an average speed of 60 miles per hour.

Instantaneous SpeedInstantaneous speed is how fast you are

traveling at a given time.

Think of a speedometer on a car. Unless you are using cruise control, the speed you are traveling changes all the time. This is instantaneous speed which shows how fast you are going at that particular instant.

Graphing speedA distance-time graph shows the change in

distance of an object over a time interval. The slope formed on the graph shows an object’s speed.

VelocityVelocity is simply speed plus direction.

Where 15 mph is a speed, 15 mph south is a velocity.

So, can you travel at a constant (unchanging) speed but still have a changing velocity?

Yes, velocity changes due to a change in speed, direction or both speed and direction.