Constant Velocity Motion Lab (18/25)
Making calculations of slope "on the fly" is complicated, because as we saw in our lab with the hallway tiles, individual data points have error in them. That's what the graph is meant to show. The red line of best fit is a much better option for getting velocity, because it incorporates all the data and averages their errors out over the whole data set. The black lines are fairly close, but the slope between each pair of points clearly varies.
But it's hard to draw a line of best fit on data that's still being collected. Perhaps because this lab had data that was collected automatically and because there's so many data points in such a short time, we can get some information by getting the slopes as with the black lines above, between two data points. If we plotted them with time on a (t,v) graph, would we get the expected pattern as with a horizontal line?
If we do this, we'll use the slope formula at the top. Look at how I did it in the v column of my table. There can't be a velocity for time 1, because there's nothing earlier to subtract from it. The next few slides are going to teach you how use a spread sheet to accomplish this.
Constant Velocity Motion Lab (18/25)
Making calculations of slope "on the fly" is complicated, because as we saw in our lab with the hallway tiles, individual data points have error in them. That's what the graph is meant to show. The red line of best fit is a much better option for getting velocity, because it incorporates all the data and averages their errors out over the whole data set. The black lines are fairly close, but the slope between each pair of points clearly varies.
But it's hard to draw a line of best fit on data that's still being collected. Perhaps because this lab had data that was collected automatically and because there's so many data points in such a short time, we can get some information by getting the slopes as with the black lines above, between two data points. If we plotted them with time on a (t,v) graph, would we get the expected pattern as with a horizontal line?
If we do this, we'll use the slope formula at the top. Look at how I did it in the v column of my table. There can't be a velocity for time 1, because there's nothing earlier to subtract from it. The next few slides are going to teach you how use a spread sheet to accomplish this.