“What if gravity acted sideways?”

Feature photo credit: MEHAU KULYK/SCIENCE PHOTO LIBRARY

“So you see students, after the projectile is launched, it follows a trajectory whose vertical position as a function of time forms a parabola while the horizontal position—yes, a question?”

“Mrs. Geddes, I understand a projectile’s behavior in Earth’s gravity, but how would all that change if gravity acted sideways?”

And, thus, the thought experiment was launched, “What if gravity acted sideways?” Here is a clever and entertaining response:

Late again? The physics of being tardy to class

by Korey Henkle, Frank Ibar, and Jean LeGrand

“Tardy again? Why can’t you ever get to class on time?” Does this reprimand sound familiar to you? I heard it so many times that I decided to make it a research question: “Why can’t I get to class on time?” I began this research effort by asking a friend to video my journey from one class, to my locker, and then to the next class. We put post-it notes on the lockers so that we could keep track of the distance travelled. The post-it notes appear on every five lockers.

Here is an excerpt of the video showing my travel to my locker. In this excerpt, I only make it past 23 lockers. Imagine what I encounter when I pass the approximately 100 lockers between any two classes:

My friends and I used movie editing software to analyze the video. We advanced the video frame-by-frame and recorded my position along with the corresponding time on the video clip. Here’s the graph we made from this data:

Position vs. time data for my travel along 23 lockers.

When I’m on the extreme edge of the lockers (at time = 0), I’m able to move with fairly stead velocity, but as soon as I get deeper into the hallway (at around 3 seconds), my travel is continually impeded. Notice the number of times that my acceleration is negative (indicated by a concave down curve in the graph) or that I’m standing still (where the slope of the graph is zero). There is one instance where my velocity is negative as indicated by the negative slope. It’s a wonder I can make it to class at all!

Teachers, bottom line is, you can’t argue with the physics of it. Being tardy to class is governed by the laws of physics, and I can’t defy that anymore than I can defy gravity. Find comfort in the fact that I am within the laws; maybe not the laws of the school, but definitely the laws of physics!