Vector & Scalar Quantities
- All quantities can be one of two types:
- A scalar
- A vector
Scalars
- Scalars are quantities that have only a magnitude
- For example, mass is a scalar quantity since it is a quantity that has no direction to it
Vectors
- Vectors have both a magnitude and a direction
- Velocity is a vector quantity since it is described with both a magnitude and a direction
- When describing the velocity of a car it is necessary to mention both its speed and the direction in which it is travelling
- For example, 60 km per hour in a Westerly direction
- Distance is a value describing only how long an object is or how far it is between two points - this means it is a scalar quantity
- Displacement on the other hand also describes the direction in which the distance is measured - this means it is a vector quantity
- For example, 100 km in a Northern direction
Comparing Scalars & Vectors
- The table below lists some common examples of scalar and vector quantities:
Scalars & Vectors Table
- Some vectors and scalars are similar to each other
- For example, the scalar quantity distance corresponds to the vector quantity displacement
- Corresponding vectors and their scalar counterparts are aligned in the table where applicable
Exam Tip
Do you have trouble figuring out if a quantity is a vector or a scalar? Just think – can this quantity have a minus sign? For example – can you have negative energy? No. Can you have negative displacement? Yes!Make sure you are comfortable with the differences between similar scalars and vectors, the most commonly confused pairings tend to be:
- Distance and displacement
- Speed and velocity
- Weight and mass