Physical Science: Interpreting Motion Graphs

To wrap-up the unit on motion, I used an activity from the 2014 EngrTEAMS summer institute at the University of Minnesota. Given position vs. time graphs for two cyclists, I first had them identify when they collided. Next, students had to decide who was at fault and construct an argument based on the graphs. There was a wide range of answers that used a lot of different evidence from the graphs, which is exactly what I was hoping for.

Physics: Graphical Solutions

Now that students have a pretty good handle on velocity vs. time graphs, they took their first stab at solving problems using graphical solutions. By the end of the hour, most students seemed pretty comfortable with this approach. I’m sure it helped that our AP Calculus teacher has students do quite a few kinematics problems and uses graphical solutions as a stepping stone to integrals. Its almost like physics and calculus are related!

Physical Science: Free Fall

Today, students explored the variables that affect how quickly an object falls. Class began with a brainstorming session to come up with as many variables as possible that might affect how quickly an object falls. Each group then picked two variables and designed their own tests. Most groups focused on weight and surface area, but one group did some quick research on different paper airplane designs, then compared different wing shapes.

Physics: Graph Stacks

Starting from position vs. time graphs, students worked on generating stacks of kinematic graphs (matching position vs. time, velocity vs. time, and acceleration vs. time graphs). Students also drew the motion maps and wrote verbal descriptions of the motion. My students who’ve taken calculus almost all started with the graphs, then had to think a bit on the motion maps and the verbal descriptions. My students currently in pre-calc tended to start with the motion maps and written descriptions, then use those to make the graphs. Both groups of students had some good conversations as they worked through the task.

Physical Science: Interpreting Motion Graphs

Students worked through a few questions based on a graph of an imaginary bike race. After a few straightforward interpretation questions like who started out the fastest and who finished first, I borrowed a page from Frank Noschese and asked students to come up with a few different ways to find the average velocity of Barry. Students then tested their approaches by using each speed to predict how long it should take Barry to finish the race. The average speed found by taking the total distance over the total time gave a result closest to his actual time, so students decided that is what we should use for average speed. They also liked that this was the easiest of all the approaches 🙂

Physics: Data Analysis

Students graphed the position vs. time data they collected yesterday for a cart rolling down a ramp. I always waffle over whether to reserve a computer lab or a netbook cart for things like this. Our netbooks are a few years old and not terribly reliable, so using them means some technical glitches and frustration that can usually be avoided in a computer lab. On the other hand, I knew that some groups would need to collect additional data or to re-measure a few points. I could have clued those groups in yesterday, but I’d much rather they use their graph to see a need for additional data and make the choice themselves, which means they need access to lab equipment while graphing. Regardless of the netbook issues, just about every group got a position vs. time graph and (hopefully) knows what they need to do to make a linearized graph. Tomorrow, we’ll prep whiteboards and discuss the results.