Idea 6of 12Builds onEvery metre countsStart to finishWhich way
Two kinds of number
Which numbers need a direction?
Today you'll discover
- a number that is complete on its own
- a number that is not finished without a direction
- the names physics gives the two kinds
Think firstTwelve metres walked. Does the way matter?
Six east then six west, or twelve straight east. Is the total walked different?
Answer first, then press Next. Compare the bracket with the arrow.
Amara's walk drawn as legs along a ground line. Pressing Next first names the thin bracket above the figures, twelve metres walked, then switches to a one-leg walk and names the solid arrow at the top, six metres east, then shows both. The last step asks what kind of number a speedometer reading is.
See the whole ideathe big idea and the key word, in one place
The big idea
Size only: a scalar. Size and direction: a vector.
For exampleTwelve metres is a scalar. Twelve metres [E] is a vector. The same digits, two different claims.
Key words
- vector
- a quantity with a size and a direction, such as displacement or velocity
- scalar
- a quantity with a size only, such as distance or speed
Ready to use it?
- Sort the course's quantities into the two kinds.