GCSE Physics - Scalar & Vector Quantities - What They Are | Examples | How to Represent Vectors

Transcript

In today's video, we're going to look at the difference between scalar and vector quantities, which can also be called scalers and vectors. Scalers are physical quantities that only have a magnitude but no direction. And remember, magnitude is just another way of saying size. And so it can be measured with a numerical value. For example, if a car travels at 22 m/s, 22 would be the magnitude of the speed.

And because speed by itself doesn't have a direction, we consider it a scalar quantity. Other scalar quantities include things like distance, mass, temperature, and time, although there are loads more. Vectors on the other hand have both a magnitude and a direction. These include things like velocity, displacement, acceleration, force, and momentum. We take a closer look at each of these quantities in other videos, though, so don't worry if you're not sure what any of them are just yet.

To help you understand the difference between scalers and vectors, imagine you start at this point A and you walk a distance of 3 km. Depending on which way you set off, you could end up anywhere on the circumference of this circle. This is because distance doesn't actually give us any idea of the direction, which is why it's a scalar quantity. However, if you'd started at A and then told us that you walked 3 km east, we'd know exactly where you ended up because you gave the exact displacement, which is a vector quantity because it has both a magnitude of 3 km and the direction of east. In order to represent vectors, we use arrows with the length of the arrow indicating the magnitude of the vector and which way is pointing indicating the direction.

So 4 km north would look like this. Whereas 2 km west would be like this because it's pointing to the left and it's only half the size of the 4 km one. We can also have negative vectors. For example, if we just had these two arrows, we could label our 2 km west one as minus 2 km east instead because it's effectively backwards in the east direction. If you haven't heard yet, you can find all of our videos on our website, cognito.org.

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