Four-and-a-third slugger

I have to admit that at the beginning of the day, I was feeling a little bit sluggish. It was chilly and raining, and my bike ride to the office was none-too-pleasant, despite wearing a rain jacket.

Yes, in the one mile, I got there feeling like four-and-a-third wet frigid slugs.

And yes, I can guess you’re asking: GROSS! A third of a slug?

Well, naturally I’m not talking about the creature. Instead, let’s get scientific here:


Thanks to my archives of pictures from my blackboard. This is from 2013, midway through the Fall Quarter, when I was teaching EA4.

The unit of mass in non-metric systems is actually a slug! In terms of weight (NOT mass), a pound is the force exerted by one slug, accelerated at 1 foot per second squared.

The gravitational acceleration on Earth is approximately 32 feet per second squared. In that case, one slug in mass corresponds to 32 pounds of weight on Earth. Therefore, with that ratio, you can figure out my weight… and I’m not ashamed of it ūüôā

How did this come up? One of my cousins posted this tweet today (hope this works…)

As it turns out, the UberFact is true. On Earth, the WEIGHT (i.e. mass times the gravitational force on the space station) is approximately 925,000 pounds. But in space, the gravitational pull is much less.

The confusion arises from the fact that pounds are a unit of weight, and not of mass.

Strangely enough, on Earth pounds are frequently converted to kilograms. This is an incorrect conversion, because pounds are a force; kilograms are a mass.

What is really done in that conversion: Pounds are converted to slugs by division by 32 (ft/s^2). Then, slugs are converted to kilograms by some conversion factor that I don’t know.

Unfortunately, when people bandy numbers around, units are often dropped, but they are of utmost importance in science and math.

It makes no sense to add pounds and kilograms, (a) because they don’t have the same units, and (b) because they don’t even have the same dimensions!

If you drop units, however, you can make “magic” in saying, for example:


(This is true if we realize that 1 = 1 day, 60 = 60 minutes, and 25 = 25 hours).

Or, shall I¬†take it up to eleven? (It’s a clickable link to an old blog post.)

210+681+2.54 = 1,815,609 +¬†ŌĶ

Before I go: I wonder if there’s ever been a 132-pound person who has hit a home run in his/her first at-bat.

If so, it would be a four-slug four-thousand slugger!


Finals Week: 2 days.

Lincoln: 9 days.

Joint Mathematics Meetings: 22 days.

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One thought on “Four-and-a-third slugger

  1. Love it, Noah! Your slug-related comments made me laugh, but also made me think – as did the pounds and kilograms bits (which I had never realised – or at least never thought out logically). I guess we often think we have nailed the plank of understanding by bandying words around – but, actually, words (and their diverse meanings) are a human construct and the universe we try to pin down is a lot more mysterious than we think! x


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