This was on a door near my office when I got to school today. I thought it was neat, so I took a picture.
This is what it looked like after school.
Today was the first day of solving problems with energy beyond energy bar charts (meaning, using K=1/2mv^2, etc). Anecdotally, I think that doing energy bar charts first qualitatively, plus starting energy empirically, has significantly increased students understanding of work and energy transfer. Thus problem solving today was a breeze. I should have some data on this in the future.
Another whiteboard below.
This note from a substitute teacher pretty much says it all. The students were whiteboarding energy bar charts while I was gone for a personal day.
I just couldn’t resist. These videos were taken before school on a voluntary basis because kids thought it would be awesome. Which it is.
Today we were comparing the area under the F vs. x graph to the final velocity of carts when they are pulled from rest with a string attached to a force detector mounted on the cart. The data for this turned out really well and clearly indicated that the area was proportional to v^2, and students picked up quickly that the slope appeared to be half the mass. The first class actually independently started looking at the units of the slope (Area of F vs. x over velocity squared, so (N*m)/(m^2/s^2) and saw then with some guidance that the unit mess actually simplifies to kg.
I’m in this weird place right now where both my classes (regular and college level physics) are in approximately the same place, but I trying two different ways to teach the same thing. In regular we went the conceptual route and introduced Energy Pie Charts and types of energy before quantifying the types of energy. In the college class I am attempting to go the empirical route. I will be blogging about this eventually on my ‘regular’ blog. Today in regular we drug carts up a track, starting and ending at rest, and found that the area under the F vs x graph was the same no matter how we got from A to B (so long as we didn’t go backwards). In this class I used this as an introduction to Work, and a reason to transition from pie charts to Bar charts. Tomorrow we whiteboard qualitative bar chart problems.
Today in my college physics class we took data to investigate how the area of the force vs. position graph was related to the change in height of a cart on a ramp, when starting and ending at rest. On Monday we will graph and whiteboard the data.
I’ve been doing a lot of thinking about the start of the Modeling Instruction Energy unit. We even talked about it for a significant part of one of our Physics teacher PLC meetings. I started Energy in regular physics about a week ago in regular physics, which started with a demo and then quickly moved on to energy pie charts. Energy pie chart whiteboarding was really fun, but I’m hoping to start my college level class off more empirically.
We did the same demo on day one, but then day two (today) we looked at the area under the Force vs. position graph as it relates to a cart being pulled up a ramp. A force detector is attached to the cart, and a string attached to the detector, and a motion detector is on the ramp pointing up. Today I asked students to pull the cart from point A to B (arbitrary), starting from rest, while graphing F vs. x, then to find the area. I had them do multiple different trials while qualitatively recording what they did while getting from A to B in different ways (speeding up, fast then slow, etc). I found out quickly that I had to have them write down whether they were moving or not when they got to point B, and in the second class I made them do trials first while not moving at B. Anyway, it didn’t take too long for them to notice that the area seemed to be the same no matter what they did if the ended at rest at B. They also noticed that the area seemed bigger if they were moving faster at B. All of this was qualitative.
We then moved on to try to establish a predictive variable for the area. Distance up the ramp didn’t work (hehe) as the same distance on different ramps doesn’t give the same area. Angle has a similar problem; the same angle with different pulling distances gives different areas. Eventually someone mentions height. So then we checked if using the same height with two different angled ramps still gives the same area, and low and behold, it does.
Tomorrow we will investigate the relationship between area and the change in height. I’ll be writing more about the differences between my two classes’ start of the Energy unit at my other blog soonish, I hope.
For a couple of years now I’ve been dropping a shot-put on silly putty to show that the kinetic energy of the shot transfers to the putty in the form of thermal energy, as measured by an increase in temperature. I wrap a Vernier temperature probe in silly putty, start data collection, and drop the shot. I usually see a 0.1 or 0.2 degree C increase in the temp, nothing too serious but it definitely gets the point across. This year I took it a bit further by scaling up to a bowling ball dropped from half a meter or so. I fully expected to break the probe, in the name of science of course, but it actually survived two drops. Even cooler was a full 1 degree C increase in the temp of the silly putty! It was also impressive when the putty (it’s actually magnetic silly putty I made in a workshop a while back) shattered pretty seriously on impact.
We started Energy Pie Charts in physics today. This one is for a wind up toy bunny that walks across a table, slowing down as it goes. It was a great starter for conversations about how the bunny started moving in the first place, as well as where the energy ended up!