Remember the first time you “saw yourself” in something? Whether it was in a piece of...Read Story
Decoding a Mask Mystery
The WPI Journal never sets out deliberately to perplex its readers, but it seems we did just that with the photograph that appeared on the back cover of the Winter 2021 issue (reproduced here). The photo shows James Imperiali ’11, one of the alumni profiled in the cover story, “A Seat at the Lab Bench.” The equation depicted on his face mask was unfamiliar to some readers.
Catharine Brown, widow of John Lott Brown ’46, a longtime trustee who served as interim president of WPI during the 1994-95 academic year, wrote, “I live in a retirement community due to my very advanced age and no one here can decipher for me what the mask on James Imperiali means. Help! Please let me know.”
Bradshaw Lupton ’72 sent this note:
“Congratulations on the LGBTQ cover. My parents sent me to a nice ‘boys’ engineering school in 1968, and I got to be in all of Jayne Rosetti’s and Lee Small’s classes [WPI’s first two women undergraduates]. They, however, did not get to be in all of mine. They were excluded from ROTC and gym.
“The back cover … I can’t figure out d3 X / dt3. Might you please decode the message?”
To help us do the decoding, we turned to Douglas Petkie, professor and head of WPI’s Department of Physics. “It is the time derivative of the acceleration (i.e., acceleration changes),” he explains. In other words, the equation describes a phenomenon in physics in which an object’s acceleration changes with respect to time. That phenomenon is called jerk.
“One example of ‘jerk’ is when you step on the accelerator in the car and get ‘jerked’ back (a very creative phrase),” Petkie adds. “You can also relate this to a changing force, which creates a changing acceleration. Pushing someone would also cause a jerk, so the time derivative is usually large (change in the force over a short time equals a larger derivative). The ‘jerk’ might not be noticeable for slow changes.”
When provided that explanation, Lupton—who said he spent all four of his WPI years “on top of Salisbury Hall playing with radios and antennas with W1YK, the ham club”—sent this reply: “I know about jerk, and didn’t get it. The good old change of acceleration with time. But what is the change of jerk with time? I feel I am the human example of that. My jerkiness has been in a state of flux for all of my now 70.7 years!”
So to close the book on this mystery, the text on the mask reads, “Don’t be a jerk. Wear your darn mask.”
We couldn’t agree more, and we’ll try not to be jerks in the future and leave our readers hanging over unexplained equations.