Speed vs. Velocity: Difference, Formulas, and Examples

By Jorge Sanchez · April 20, 2026 · 5 min read

The Key Difference: Scalar vs. Vector

Speed Formula

Where: s = speed, d = distance, t = time

Worked Examples

Example 1: Find Speed

A car travels 150 miles in 2.5 hours. What is its average speed?

Example 2: Find Distance

A train travels at 80 mph for 3.5 hours. How far does it go?

Example 3: Find Time

How long to travel 200 km at 100 km/h?

Average Speed vs. Instantaneous Speed

• Average speed = total distance ÷ total time (what you calculate over a whole trip)
• Instantaneous speed = speed at a specific moment (what your speedometer shows)

A road trip of 300 miles in 5 hours averages 60 mph — even if you hit 80 mph on the highway and stopped for lunch.

Velocity in Physics

Velocity is crucial in physics because direction matters for forces, momentum, and projectile motion. Key concepts:

• An object moving in a circle at constant speed has changing velocity (direction changes)
• Acceleration is the rate of change of velocity, not speed
• Displacement (used in velocity) measures shortest path from start to end — not total distance traveled

Example: You walk 3 km north and 3 km south. Total distance = 6 km. Displacement = 0 km. Average velocity = 0 (you ended where you started).

Common Speed Conversions