Multiple choiceQuestion 1 · Recall
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By the end you can explain the difference between scalar and vector quantities and sort the quantities in this syllabus into each group.
Scalar quantity
A quantity that has magnitude only, for example mass, time or energy.
Vector quantity
A quantity that has both magnitude and direction, for example displacement, velocity or force.
"Walk 300 m" isn't much use as directions. "Walk 300 m north" is. The distance (300 m) is a scalar; the displacement (300 m north) is a vector. Draw a vector as an arrow: its length shows the magnitude, its direction shows… the direction.
| Scalars (magnitude only) | Vectors (magnitude and direction) |
|---|---|
| distance | displacement |
| speed | velocity |
| mass | weight (a force) |
| time | acceleration |
| energy, work done | force (tension, friction, drag, upthrust…) |
| power | momentum |
| pressure | electric field strength |
| density, volume | gravitational field strength |
| temperature | |
| charge, current, potential difference, resistance |
Learn the pairs in the first three rows: they are the favourite exam traps.