Posts Tagged ‘uncertainty’
This is for commenter JimP. How do you take into account uncertainty when using video analysis? A great question. The first thing to think about is where does the uncertainty come from? My first guess would that it would be from the user. Where does the user click? Is [...]
This is really a lab that I have students do, but I am pretty sure they don’t read this blog – so it is ok. If they are reading this, hi!
We have these projectile cannons that shoot small balls. In order to look at projectile motion, they need to first determine the launch [...]
This Giant water slide video is extremely popular on the internets. Maybe you have not seen it (doubtful), then here it is:
This is such an incredible stunt that the very first question that comes up is – fake? or not fake? From my previous analysis, I can say:
Even though there is some [...]
I think the Mythbusters have a wonderful opportunity for educational outreach. Take this week’s episode. One myth was to see if arrows fired from a moving horse penetrated more than arrows fired from a standing position. They first did this with real horses, but they said the data was not convincing.
One of the simple ways of determining the uncertainty of a calculated quantity is to use the uncertainty of the measured variables and find the max and min that calculated quantity can be. The example I used was in calculating the uncertainty for the area of a rectangle. So, the maximum and min areas would be:
Some time ago, I wrote about the awesome things the Greeks did in astronomy. Basically they calculated the size of the Earth, distance and size of the moon and distance and size of the sun. The value obtained for the distance to the sun was a bit off, but still a bang up job if you ask me. (where bang-up is meant as a good thing) If the greeks were in my introductory physics lab, they would need to include uncertainties with their measurements. What would the uncertainty in the final value look like?
One of the problems is that students don’t really have a good understanding of data analysis. For me, statistical analysis is just something to do with data. It isn’t absolutely true. So, it doesn’t really matter that students use sophisticated tests on their data. The important point is they use some type of test to compare data.
Suppose I am working on a problem and I wish to calculate the density of something. I measure the mass to be m = 24.5 grams and the volume is V = 10 cm3. In this case the density would be:
ALERT! ALERT! ALERT! This is not a test!!!! Something is drastically [...]