0Definition:
Speed = Distance travelled per unit time
Speed=DistanceTime\text{Speed} = \frac{\text{Distance}}{\text{Time}}Speed=TimeDistance
Important Points:
-
It has no direction
-
It is a scalar quantity
-
It is always positive
Example:
If a car travels 100 m in 10 s:
Speed=10010=10 m/s\text{Speed} = \frac{100}{10} = 10 \text{ m/s}Speed=10100=10 m/s
We only know how fast — not where.
🔹 2️⃣ Velocity
✅ Definition:
Velocity = Displacement per unit time
Velocity=DisplacementTime\text{Velocity} = \frac{\text{Displacement}}{\text{Time}}Velocity=TimeDisplacement
Important Points:
-
It has direction
-
It is a vector quantity
-
It can be positive, negative, or zero
Example:
If a car moves 10 m/s east, that is velocity.
Direction matters.
🎯 Key Difference
| Speed | Velocity |
|---|---|
| Based on distance | Based on displacement |
| No direction | Has direction |
| Scalar | Vector |
| Always positive | Can be +, −, or 0 |
🧠 Simple Example to Understand
Suppose you walk:
-
5 m forward
-
Then 5 m back
Distance = 10 m
Displacement = 0 m
If total time = 10 s:
Speed = 10/10 = 1 m/s
Velocity = 0/10 = 0 m/s
👉 You moved, so speed is not zero.
👉 But you ended where you started, so velocity is zero.
📌 Average Speed vs Average Velocity
Average Speed:
Total DistanceTotal Time\frac{\text{Total Distance}}{\text{Total Time}}Total TimeTotal Distance
Average Velocity:
Total DisplacementTotal Time\frac{\text{Total Displacement}}{\text{Total Time}}Total TimeTotal Displacement
They are equal only in straight-line motion without changing direction.
🚀 In Simple Words
Speed tells:
“How fast?”
Velocity tells:
“How fast and in which direction?”
