Physics with Portals

I took a deeper look at my experiment from the last few posts and made a couple graphs.

The first details the difference between predicted and actual values for the magnitude of the cube’s velocity as it flies through the air:

Notice how the actual data strangely has a small dip at the beginning. I’m not sure where that’s coming from. Let’s take a look at its X and Y velocities:

The predicted values run a little bit farther than the actual values because I let my simulation (i.e. Excel formula) run a little bit longer than it takes for the cube to hit the ground.

There seems to be a weird jolt around 0.2 s. I’m not really sure what’s going on here. If you’ve got any ideas, please let me know.

I also looked into the difference between predicted and actual values for the height of the cube as it flies through the air:

I had to eyeball the height of the cube as it fell, which led to the wonky graph line. Regardless (and unsurprisingly), it still appears as if it takes a little bit longer for the cube to hit the ground than is predicted. It’s safe to assume that this is because of air resistance.

Any ideas about what’s going on here? Any ideas for new tests? Let me know!

I apologize for the dearth of posts lately. School started this week (!) so I’ve been insanely busy. I’m planning on giving my students their first hands-on experience with Portal 2 in about two weeks. They’ll be running labs that have been almost a year in the making. Of course, anything and everything that happens with portals in class will be documented here. Stay tuned.