Moving Rocks

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Although I should go through the calculations, I choose not to. Partly because the deed is done, and partly because of the general relationship between number of equations I produce on the processes around the house their inverse relationship to the general state of harmony.

At any rate, I will say that I should run the numbers.

My wife recently returned from a 435-mile trip from her parents with a number of rocks in the car. Yes, rocks. These are not a few geologic samples. These are for landscaping. A large number of them. She thought they were pretty. I thought, well, if we look around here, we could buy rocks within 10 miles of our home and even though we would have to pay for them, the cost may well be far below the cost of the “free” rocks she brought home. Two words need applied: transport costs.

If we take the weight of the rocks, the decrease in fuel efficiency due to the extra weight of the rocks in the car, the cost of extra gas to account for the increase in weight of the vehicle with the rocks in it. then we start to approach the true cost of the rocks.

For bringing back rocks to be worth it:

Cost of transport of “free” rocks < cost of local “non-free” rocks

There is a transport cost even for the local rocks, but we will assume this is negligible, being so close, meaning far less that the 435 miles of transport of the rocks from out of state.

Again, the numbers were not run, if only for the sake of peace and tranquility in the home.

Running Numbers on the Elevator


For an engineer, running calculations and numbers in your head is an occurrence of frequent timing. It is not our fault. The world is constantly presenting us with situations for number crunching, usually to be more efficient, make sure we are on time, or be content that the building won’t collapse.

Case in point – the elevator. I got on an elevator the other day and saw posted a sign that is visible in various forms on most elevators: Weight Limit 4000 lbs.

Am I safe in here? What if I am in here and a number of heavy people get on at the next floor before I have a chance to exit? So, my mind starts going: If heavy people, let’s say 250 pounds each, get on the elevator:

4000/250 = 16, so it would take 16 people each weighing, or averaging, 250 pounds to max out the elevator capacity. Though unlikely, can they even fit?

I estimated the elevator to be about 6 ft by 7 ft, or 42 square feet. This means each person would need to fit with:

42/16 = 2.625 square feet, or in a square with a side of 1.62 feet. That is 19.44 inches. This would be an extremely tight fit. I think my shoulders are about this width, and I thought about the stagger and organization of the squares. Fitting 16 people of that size in here would be difficult, not to mention the low odds of that many people of that size showing up at the same time. But not impossible.

I convinced myself that not only is the chance of that many big people wanting to enter at the same time very low, but, and here is the real comforting thought, they always throw in a good factor of safety on these things. Without looking this up on the internet, I was at ease riding the elevator. Until that delivery guy wheeled into the elevator a flatbed containing numerous boxes that may well be holding lead plates or gold bars, elements with very high specific gravities.

The calculations begin all over again…


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While engineers generally (meaning constantly) shun movies or shows with too much emotion, they are not unreasonable about it. An engineer may decide that he can respect a story that is about the deep emotional things of life if it contains at least some calculations. Case in point, Rent.

The engineer will likely not get or desire to get the deep emotional angst, or hope that the show has to offer. But he can appreciate that they have calculated the number of minutes in one year, AND they made an entire song out of it!

Calculations are good for movies or theater and the engineer.

Engineers Can Be Fun on Road Trips, Too

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I have a “friend”, at least in the sense that he is on my friend list on Facebook. I will call him, “Eric”, since that is his name. He is a musician.

The other day, “Eric” posted on FB that he was in the car on a trip with his kids and they were playing DJ with the songs being played on the radio. What do you expect? Music is his life. And I am guessing that the kids were mildly amused.

However, I am here to report that engineers can be great fun for kids while riding in the car, too.  Just like people such as “Eric”, an engineer will use his skills to fascinate the children. Here are a few tried and true ways:

– After a stop to fill up,  the engineer can give the odometer readings for then and the previous stop and give the number of gallons of gas purchased and then ask, “Can someone be the first to calculate the gas mileage we are getting?” This can be made more challenging by giving the eager youngsters the price of gas per gallon and the total amount of the bill, instead of the number of gallons, and by taking away their calculators.

– While traveling through an area with a lot of bridges, the engineer can ask the kids to identify at least 5 different types of bridges!

– For varying speeds and direction of travel, have the children sketch out the vectors on a map, and break each down into it’s component vectors.

Yes, “Eric”, you may have music, but what happens when you are in the middle of nowhere without a good FM station to listen to? The engineer can bring along a few calculators or some graph paper or maybe just his love of equations, and the kids will have wonderful memories for years in the future of road trips with the family.

You Might Be an Engineer If…

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– you politely ask your wife to quit gushing about the “gorgeous waterfall” you are visiting on your vacation so that you can complete estimations in your head on the volume and rate of water flow and to run some preliminary calculations on how much electricity could be harnessed from this resource.

Calculations Yet To Do


I recycle. My favorite thing to recycle is aluminum cans. This is because I get money for them.

When I am at work, at times I will drink a soft drink from an aluminum can. Sure, I can throw it in their recycling container, but then I wouldn’t get the money for it. Instead, I keep the cans and take them home once in a while. However, this has bothered me  because I also know that adding the cans to my commute home adds weight to my vehicle and, therefore, decreases the mileage, the number of miles per gallon of gasoline.  By how much? I haven’t done the calculation yet. But if the cost of transport is higher per can than the amount of money I will get for that can, it doesn’t make sense to take the can home, and I might as well recycle it at the office and, grrrrr, have someone else get the money for it.

This is a calculation I have yet to do….

(Am I the only one to think about things like this?)

In the interim, I have derived a simple solution to the dilemma. The solution is to only bring the cans home on days that I am a passenger in my car pool and my car is not being burdened by aluminum. Then the additional cost due the extra mileage is not encountered at all (by me).