Your mom is driving your car at 30 mph. That’s her speed. She’s driving the car north to drop you off at school at 30 mph. That’s her velocity. Scientists call speed a SCALAR because it has only one attribute, magnitude or speed. Velocity is a vector. It has two attributes, magnitude (speed) and direction.
- So why does velocity matter in real life? Say, for example, you were on a boat going 5 knots per hour. That’s the boat’s speed. You know you want to reach a point 10 miles down the shore. Cross winds are capable of slowly and subtly blowing the boat off course, changing the direction you’re traveling. If you understand velocity (direction plus speed) and you’re aware of cross winds, you can change your course, gradually moving inland so you’re not blown out to sea.
- Speed: a unit of measurement in time from one point to another, typically measured in miles per hour
- Velocity: a measurement of both speed and direction
- Vector: having two attributes