Speed vs. Velocity - Video Lesson

Welcome to our series on Doppler ultrasound in medical sonography. This lesson looks at key differences between speed and velocity, and why understanding these concepts is crucial for interpreting Doppler measurements. Let's get started with a quick description of the essential differences between speed and velocity. In the simplest technical terms, speed is defined by magnitude alone. In other words, how fast is something going? Velocity on the other hand is defined by both magnitude and direction. So how fast and in what direction is something going? It may be easier to understand with this illustration. Imagine a car cruising down a highway at sixty miles per hour. That number, sixty miles per hour, tells us the car's speed. It tells us how fast something is moving, but it doesn't tell us where it's headed. Now, let's add a direction to that motion. The car is moving north at sixty miles per hour.