Speed and Velocity (8th)

Speed is a rate, or a number that tells us how fast something happens. In this case, it tells us how fast a distance is traveled. For example, if someone rides a bike 2 m/s, they are traveling 2 meters every second. We could use that to track how far they have traveled for a certain amount of time or how long it would take them to arrive at a destination. We often here speed measured in mph or miles per hour; which would tell us how far someone would get if they traveled for an hour at a constant speed.

There are two types of speed. We could look at average speed, the total distance traveled / total time it takes. Average speed would be what you calculate for a race or road trip: John traveled 12 km to the store and it took 20 min to get there. We simply look at how far he traveled and how long it took. Stoplights, changes in speed, etc don't matter here. Instantaneous speed is a measure of how fast on object is traveling at a given instant in time. For example, if you get pulled over for speeding, the cop tells you how fast you were traveling when he caught you with his radar.

Velocity is similar to speed, but it has a direction. Two ways to change velocity are to change speed or change direction. Objects very rarely have a constant velocity for long because objects usually change speed or direction frequently.