Motion · Topic 1 of 17

Motion: Distance, Speed & Velocity

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Physics · motion

Motion: Distance, Speed & Velocity

Speed and distance are scalars (size only); velocity and displacement are vectors (size plus direction). Average speed is total distance over total time.

01 · Scalar vs vectorVector = magnitude + direction

02 · SpeedAvg speed = total distance ÷ total time

03 · VelocityVelocity = displacement ÷ time

What it is

Scalar = size only; vector = size plus direction must know

Distance = path length; displacement = final − initial position must know

Scalars: distance, speed, time; vectors: displacement, velocity, force

Same speed, new direction = a new velocity (rounding a corner)

The rules

In one dimension the sign is the direction (+ right/up, − left/down)

Speedometer = instantaneous speed (velocity's size, no direction)

Rearrange: distance = speed × time; time = distance ÷ speed

Know by heart

Average speed = total distance ÷ total time (scalar) must know

Average velocity = displacement ÷ time (vector, has a direction) must know

Speed and velocity are measured in m/s (also km/h, mph)

Worked examples

120 m in 80 s → 120 ÷ 80 = 1.5 m/s

30 km in 1 h + 30 km in 2 h → 60 km ÷ 3 h = 20 km/h (not 22.5)

12 m E then 3 m W in 15 s → speed 1.0 m/s, velocity 0.6 m/s E

Speed or velocity?

Commonly confused

	Distance / speed	Displacement / velocity
Type	Scalar (size only)	Vector (size + direction)
Measures	Total length of the path	Straight-line change in position
Formula	Speed = distance ÷ time	Velocity = displacement ÷ time
Round trip home	Not zero	Zero

Common mistakes

Distance can exceed displacement — equal only for a one-way straight trip

Round trip: displacement and average velocity are 0, speed is not

Multi-leg trip: total distance ÷ total time, never average the speeds

More detail

Show 1 more fact

km/h ÷ 3.6 = m/s (1000 m per 3600 s)

Pearl

Speed asks how far along the path; velocity asks how far from the start, and which way.

Sources · OpenStax College Physics 2e §2.1 Displacement · OpenStax College Physics 2e §2.2 Vectors, Scalars, and Coordinate Systems · OpenStax College Physics 2e §2.3 Time, Velocity, and Speed · Union Test Prep — HESI Physics study guide, p. 1: Motion, speed, velocity · NurseHub — HESI A2 Physics course (topic list: Nature of Motion) · Union Test Prep — HESI Physics study guide, p. 2: Uniform circular motion (same speed, changing velocity) · Built from the verified NurseSavvy HESI A2 fact map (facts reviewed 2026-10-16). HESI is a trademark of Elsevier; NurseSavvy is not affiliated with Elsevier.

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