Distance, Speed, and Velocity Basics
Understanding scalar and vector quantities is your first step to mastering motion in physics. Scalars only have a magnitude (size), whilst vectors have both magnitude and direction - think of it like the difference between saying "I'm going 4 m/s" versus "I'm going 4 m/s east".
Distance and speed are scalar quantities because they don't worry about direction. If someone runs 550m in any direction, that's still 550m of distance covered. Displacement and velocity, however, are vectors because direction matters - walking 4 m/s north is completely different from walking 4 m/s south.
The speed formula is dead simple: Speed = distance travelled ÷ time taken, or S = d/t. For example, if you travel 550m in 10 seconds, your speed is 550 ÷ 10 = 55 m/s. Velocity uses the same calculation but with displacement instead of distance: V = displacement ÷ time.
Quick Tip: Remember that velocity is just speed with a direction attached - so 55 m/s east is a velocity, whilst 55 m/s on its own is just speed.