Every quantity in physics can be classified as either a scalar or vector.
Vectors are quantities that are represented by both a magnitude and a direction.
Scalars are quantities that are represented by only a magnitude.
When answering a question or problem, it is helpful to understand whether the quantity is a scalar or vector as it will influence the result.
Examples:
1) If a car travels 50 units east and then 40 units west, then what is the distance the car has traveled?
Since distance is a scalar quantity, the direction of the car does not aid us in attempting to find the solution. Thus we can add 50 units and 40 units and we get the car travels a total of 90 units.
The distance the car travels in 90 units.
2) If a car travels 50 units east and then 40 units west, then what is the displacement of the car?
Since displacement is a vector quantity, the direction of the car does aid us in finding the solution. We must consider that the car travels 50 units east, and doubles back 40 meters west. Therefore after the car’s trip, the car has only travelled 10 units in the east direction from its original point.
The displacement of the car is 10 units [east].
There is a difference between the magnitude of both answer. Additionally, the displacement of the car has a direction attached to it. We must consider direction in our final answer because we are working with a vector quantity, displacement.
Examples of scalar quantities: Distance (m), Speed (m/s), Temperature (0C), Mass (g)
Examples of vector quantities: Displacement (m [north]), Velocity (m/s [south]), Acceleration (m/s2 [west])
This article was written for you by Jeremie, one of the tutors with Test Prep Test Prep Academy.
