Scalar and vector
A scalar has size only, like 5 kg. A vector has size and direction, like 5 N to the left.
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Analogy
A scalar is 'drive 10 km'. A vector is 'drive 10 km north'.
Example
Walk 300 m east, then 400 m north.Distance = 300 + 400 = 700 m (scalar)Displacement = 500 m, straight line(a 3-4-5 triangle) (vector)
In practice
Forces, velocity and displacement are vectors. Mass, time, speed and energy are scalars.
Practice
Flashcards
- What is the difference between speed and velocity?Velocity is speed in a given direction. Speed has no direction.
- Name one scalar and one vector.Scalar: mass or speed. Vector: force or velocity.
Interview questions
- Explain the difference between distance and displacement, with an example.
- Distance is the total path length and is a scalar
- Displacement is the straight-line change in position and is a vector
- Example: a full lap has distance but zero displacement
Questions people ask
What is the difference between distance and displacement?
Distance is the total length of the path you travelled, and it has no direction. Displacement is the straight-line gap from start to finish, with a direction. If you run one full lap of a track, your distance is the lap length but your displacement is zero.
How do you show a vector on a diagram?
Draw an arrow. The length of the arrow shows the size, and the way it points shows the direction. A force of 10 N should have an arrow twice as long as a force of 5 N pointing the same way, so you can compare them at a glance.