One day in mid-December many years ago my mother was on a shopping trip with four kids in the car: a 6-year-old, a 5-year-old, a 3-year-old, and a newborn. In the middle of nowhere we got a flat tire. Calling a tow truck would have been very expensive, and it wasn’t even totally obvious how to get to a phone. My mother had a pretty good idea how to change a tire, but she wasn’t going to do it herself, because she was recovering from a dislocated shoulder. So it became my job. The spare tire weighed more than I could lift, so it took some fancy leverage to get it out of the trunk. The OEM lug-wrench was useless. However, I noticed that there was a 28" long breaker bar with just the right socket lying in the bottom of the spare tire well. That still didn’t solve the problem. I had always been big for my age, but the age in question was 6. I weighed 50 pounds at most. The lug nuts had been put on with an air impact wrench, and they had picked up some rust since then. My strength was not going to get the job done. Then I noticed a 30" piece of water pipe in the bottom of the spare tire well. I wondered what it was doing there. It seemed a remarkable coincidence that it was just exactly the right diameter to slip over the end of the wrench. That gave me more than four feet of lever arm. I jumped on the end, and klunk the nut moved a little bit. And so on.......

I didn’t think too much of it at the time. For me it was just another chore to be done.

Figure 1: Lucky Snipe and Breaker Bar

That evening over dinner my mother recounted the story. My father deadpanned “Sure is lucky somebody put that snipe in the car.” That tells you something about his sense of humor, and his definition of luck. He was a big strong guy, and would never need such a thing, but years ago he put it in the car anyway.

Later that evening it was explained to me that money did not grow on trees, and the cost of a tow truck would have wiped out the Christmas-shopping budget.

I had always been curious about physics, but from that point on it was more than an idle curiosity. There’s a lesson here, but it’s not the sort of thing you can teach in school.

• I suppose you could formulate a multiple-guess quiz question about mechanical advantage, so that it factors into the test score and course grade ... but the actual “feel” of jumping on the snipe is something else entirely.
• The “feel” of having a significant impact on Christmas is something else yet again.

Bottom line:

1. Utility is the best mnemonic.
2. Some people are luckier than others ... for a reason.

1  References

1.

John Denker,
“The Lucky Oven”
www.av8n.com/physics/lucky-oven.htm