[Music] hi and welcome back to three sighs lessons cold okay by the end of this video you should be able to describe what's meant by scalar and vector quantities giving examples you should then be able to describe how a vector quantity can be represented by an arrow okay I'm showing you here a list of different quantities that we often measure or calculate in physics we've got mass at temperature speed energy distance and time now all of these are examples of scalar quantities scalar quantities have magnitude only and the word magnitude means size scalar quantities do not have a direction so we're going to look at distance as an example of a scalar quantity I'm showing you here a map imagine that you wanted to go from point A to point B this shows a possible route now if you took this route you would travel a distance of around 800 meters but the key point is that distance gives us no idea of the direction and that's because distance is a scalar quantity all of these locations are a distance of 800 meters from a starting point so simply stating a distance does not tell us where we're going so as we said before scalar quantities have magnitude in other words size only remember that scalar quantities do not have a direction okay here are some other quantities that we can measure or calculate in physics we've got displacement weight force velocity acceleration aren't momentum now these are all vector quantities but because these all have both magnitude and direction so gone back to the previous example we saw that distance is a scalar quantity because it gives us no idea about direction however displacement is a vector quantity and that's because displacement is distance in a specific direction so in a journey we've travelled a distance of 800 meters however our displacement is 500 meters due west from a starting point so can you see that with displacement we have to state the magnitude in this case 500 meters and the direction which in this case is due west now we can represent vectors using an arrow and I've done that with displacement on this map the length of the arrow represents the magnitude of the vector and the direction of the arrow represents the direction of the vector we're going to be looking at all of these vectors in the topic on forces and you'll be seeing I was being used in each case remember you're fine plenty of questions on scalar and vector quantities in my vision workbook and you can get that by clicking on the link above [Music]