 So now we can look at displacement in one dimension. Displacement, if you think about the word, to displace means to move something. So the displacement is how much it's moved, or it's change in position. Because position has a dimension of length, displacement also has that same dimension of type length. So it can use any of the standard length measurements, but our typical metric unit is going to be meters. The variable notation that we use to represent displacement, this change in position, is this one over here. Now, the x represents the position. This triangle is actually the Greek letter delta. So delta x is the change in position, and that Greek delta is used in physics always to represent a change in something. So let's take a graphical view of displacement. So let's say I've got my number line along this horizontal line, and I'm talking about an object which moves from a position of four meters and goes to a position of seven meters. Well, I would represent the displacement then as an arrow which starts on a position of four and points towards a position of seven. So my vector arrow shows me how long, how big the change in position was, and which direction it points in. This one points towards the right or in the positive direction. As an second example, I could move from three meters to one meter. Again, I show it as an arrow. In this case, I'm moving towards the left. Remember, positions can be negative, so our displacements can involve negative positions as well. And if I'm moving from minus five meters to minus one meters, I could show that as an arrow along the number line. Now, if I want an equation, my displacement or my delta x is equal to the final position minus the initial position. So it's just a subtraction of those two, paying careful attention to whether they're positive or negative values. So let's look at these examples. These are the same ones that I showed graphically with my arrows. If I move from a position of four meters to a position of seven meters, then my final position is my seven meters. My initial position was my four meters. And the displacement is calculated by seven meters minus four meters, giving me a displacement of positive three meters. If I'm moving from three meters to one meters, then three meters is my initial position. One meter is my final position. And I've moved backwards. I've moved a displacement of negative two meters. If you've got negative positions, it's a good idea to use your parentheses to keep track of things. In this case, because of the negative and the negative, I actually have a displacement of positive four meters. It was really clear looking at it on the number line. We also want to keep our positives and negatives in place when we're doing our calculations. So this again is our brief introduction to displacement in one dimension. You'll get plenty of practice finding these displacements.