1.1.A.1–2Concept
Scalars are quantities described by magnitude only; vectors are quantities described by both magnitude and direction. Vectors can be visually modeled as arrows with appropriate direction and lengths proportional to their magnitude.
ExampleSpeedometer vs. GPS reading1 / 3
A car's speedometer reads 25 m/s. A GPS report instead says the car's velocity is 25 m/s, due east. (a) Which of these two numbers is a scalar, and which is a vector? (b) Explain what information the vector version provides that the scalar version does not.
Try it on paper first, then reveal each step to check your work.
Step 1 — The speedometer reading
25 m/s with no direction attached is a scalar — it reports a magnitude (speed) and nothing more.