Now you know how to use position, distance and displacement to describe where something moves, but what about how fast? How can you describe the difference between how fast you ride a bike and how fast a racecar zooms around a track? Or how slow an ant crawls across the sidewalk and a cat stalks a bird?
Watch this animation to find out more about using speed to explain how fast or slow something moves as well as where direction fits in. As you watch the segment, you might want to check the definitions of specific terms. In addition to the glossary words listed above, the terms constant, speed and velocity will be described.
Stop the animation at any time, watch it again, or read the transcript.
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Beyond the position, direction, distance and displacement of an object, other important factors in this whole “motion” thing are speed and velocity.
Speed is the measurement of how far an object moves divided by how long it takes to move. And although the concepts of “fast” and “slow” are pretty obvious to the casual observer, the speed of an object is a measurement of the distance divided by the time. Miles per hour, meters per second, inches per year. Things can move at a constant rate, or move at changing rates. You can measure the speed at a certain instant, or an overall average speed of the entirety of the movement. Because it is measuring distance over time, these are all measurements of speed.
Then there is velocity. Velocity is similar to speed, but it measures time, distance, and direction of an object. So 15mph is a measurement of speed. But 15mph west is its velocity. Velocity come in handy when your simple trip becomes a bit less simple.
Each of these measurements- speed and velocity--helps to describe the motion of an object. Which comes in handy for all the things that move in your life.
In the space below write a definition of speed. Then describe how velocity is similar to speed and how it is different. Finally, describe how you can tell from its speed how quickly an object is moving. i