Wednesday, January 18, 2023

Financial Math and the Number of Cylinders In An Internal Combustion Engine

Going over the previous day's homework assignment in Financial Math, we came across a problem that went something like this:  A shop charges $40 for an oil change, $70 for a tune-up on a 4-cylinder car, $80 for a tune-up on a 6-cylinder car, and $90 for a tune-up on an 8-cylinder car.  How much did the shop make if they did 5 oil changes, 6 4-cylinder car tune-ups, ....

Yes, folks, that's in a high school math class.  Which is full of mostly seniors.

I gave the answer, and then something hit me.  I asked how many students had no idea what 4-cylinder, 6-cylinder, and 8-cylinder engines meant.  Over half the students raised their hands, and I couldn't just let that go.  Today's lesson was going to be a short one and the homework assignment was brief, leaving plenty of class time I could make use of, so I spent several minutes talking about engines.

I started by explaining the 4 strokes of a 4-stroke engine:  intake, compression, combustion, and exhaust.  My drawing on the board was very elementary since I wanted to keep things as simple as possible, and I was surprised how many students opted to learn about this rather than complete their assignment in class.  After walking them through the 4 strokes, I showed this video that used animated graphics to reinforce and extend what I had just taught:

Then we went into the difference between a "straight" configuration and a V configuration of the cylinders, and lastly discussed what is meant by a "5.0 liter engine".  This entire discussion, including the video, took significantly less than 15 minutes.

I think it was worthwhile.

7 comments:

  1. Anonymous8:10 PM

    When I was sharing a cubicle space with a jet engine guy back in the 80s, I learned a different nomenclature for the four stages, but I guess mine doesn't work in high school.

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  2. We used to have a shop class that was titled "Small Engines". You disassembled a lawn mower to the last screw, and put it together.

    The final exam was if it functioned when you assembled it, and it worked.

    Good class, learned lots and it was a nice break from paper and pencil classes.

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  3. Nothing wrong with such a class.

    My dad was a master machinist, and there wasn't an engine he couldn't fix. Still, I didn't take shop classes in high school. My school offered wood, metal, electronics, car, and construction shop classes, and I understand that in the years after I left they added upholstery. I wonder how many of those they still offer.

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  4. When I taught Physical Science, for some reason, internal combustion engines were part of the curriculum. The class was for the non-academically inclined students. While grading the quiz, I was surprised that they all got: Intake, Compression, Power and Exhaust.

    If the quiz asked them what period we had class, a few would have botched it. The next day, I asked how they all remembered the order. That's when I learned about Insane Clown Posse.

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  5. Hugh Jones4:20 PM

    I learned the four stages as Suck-Squeeze-Bang-Blow.

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  6. Anonymous2:27 PM

    @Hugh Jones, that was the one I was alluding to in the first comment.

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  7. I like it!

    I had a friend who, while a cadet at the Air Force Academy, was in the Drum and Bugle Corps, which was colloquially known as Beat and Blow.

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