hi everyone and welcome to this video today I'm going to explain to you how to calculate a gradient now before you do something like that it's always very important to know what you are doing uh because that would make it easier to remember now the gradient is basically how steep a slope is between two different places now that is the simplest way of explaining it so the formula is gradient equals vertical interval over horizontal equivalent now what does this tell you it tells you the vertical interval is the difference in height between those two locations on the map so it's a simple calculation 200us 140 or something like that and the horizontal equivalent is simply the distance between those two places so you are going to calculate if you have 25 cm on your map then you are going to calculate the real distance between those two places so let's have a look at our map so here we have a few contour lines um now it's important to understand what they represent a contour line is a line that connects every place uh with the same altitude so in other words on this line here for example each and every place on the line doesn't matter where we go it could be here it could be there or here every single place on this line is 1,020 m above sea level right so your teacher might ask you to calculate the gradient between point a and point B now first thing you need to know is what is the height of point a so there's there are no numbers on this side of the map but if you just trace this line if you go all along this line You'll see that it's 1,20 because every place on this line is20 so that's your first number 1,20 M and then you want to know what is the height of this specific place over here and you'll see that it's 1,100 m above sea level the next thing you need to know is the distance between these two places and here uh it's not really 25 but but let's say it's 25 cm and so what you are going to do is you are going to calculate the real distance now I posted a video on the distance calculation um using different map scales so if you'd like to see that click the link below um but I'm not going to go into too much detail what you are going to do uh here is you're going to say 25 cm times the scale it will give you a certain number and we'll take it from there so let's look at how it's done so firstly we want to find the difference in height so it's a 1,100 - 1,20 and here we are going to calculate the distance it's 25 cm * 50,000 so remember we always use the scale when we calculate the real distance now 1,100 - 1,20 is 80 M that's very easy and here we have to do a little calculation this will give you a total of 1,250,000 [Music] CM now obviously you want to convert cm to kilomet um so how do we do this we say 1,250,000 divided by 100 ,000 and this will give you so let's just write that amount this will give you a total of 12a 5 km now obviously this we are going to write the final answer as a ratio and that is why we can't compare meters with kilometers and that is why we are going to convert this to meters so this would give you I don't have enough space to write everything out but this is 12, ,500 M 12,500 M now we want to simplify these numbers and so what we are going to do is we are going to write a one here how did I get the 180 / 80 so you do the same below the line 12,500 / 80 and it gives you a total of 156.25 let's make it three now some of you might say but this doesn't make any sense you can't write a fraction like this and it's absolutely correct you can't write fractions like this but this isn't a fraction this is a ratio this is a nothing to do with maths or or fractions or anything like that so this is how we are going to write it it's 1 2 1 5 6A 3 now some of you will remember what this ratio is telling us it tells us that for every 1563 M that we travel from point A to point B there will be an increase in height of 1 M now what does this tell us about the slope it tells us that it's a very very gentle slope because you have to travel quite a long distance before there's an increase uh in height of only 1 M so the smaller this number here the steeper the slope so let's say there's another um gradient and the answer is 1 2 2 then it means the slope is very steep because for every 2 m that you travel from point x to point Y there's an increase in height of 1 M and that is quite steep so I hope you understand how to calculate a gradient now I've also posted other videos on how to calculate distance I explained map different map scales in in in detail and I've also posted a video on how to to measure a bearing and so on so please feel free to click one of the links below if you need more information on some of these topics and remember to subscribe thanks for watching see you next time