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.

1 + 1 =

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This equation, and the answer to it, is of terrific value to the engineer. When deciding whether to ask a girl to marry him, the engineer will do an analysis. 1 + 1 = ________. The answer typically is 1.39664 or 1.43428. If it is less than 2, then it would make sense to get married. Marriage, as all things for the engineer, must be about efficiency. Whether the equation is for finances, which is a great asset in the engineer’s mind (living at lower cost), or for time savings (less time traveling around if not married and less coordination of schedules – he surmises), then if the number is less than 2, and it really makes sense to get married.

Sure, there is that vague concept of love, but how do you quantify that?

Stick with the calculations and a content life will be with that efficient couple.

Guess I should have written this one on Valentine’s Day.

dy/dx

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This concept is used in many equations engineers love – it is the rate of change. The rate of change, the change in a value y per change in a value x. That almost makes me giddy just writing that.

dy/dx is used so frequently and is so powerful in engineering applications, from falling objects, to increasing pressure with depth in a liquid, to electrical applications, flow, strength of materials, and the list goes on.

To make things even more fantabulous, engineers will frequently evaluate rate of change of rate of change. Woah! What-what?

Think about measuring an object moving – falling or rolling – in one direction. We can measure that rate of change of position in terms of dy/dx, or change in distance over change in time. This is velocity, speed if it is in one direction. But what if the velocity changes? Then we measure the change in velocity over time, or in other words, the change in distance over time over time, or something like that. It makes more sense in an equation. This is acceleration. What happens if we measure the change in acceleration? Well, we may just be going back in time. No. I am kidding.

But rate of change is powerful, and engineers use it frequently. An engineer could even use it to measure non-engineering things, like the rate of change in time for, say, his wife to get ready to leave for the evening, with change in the years of marriage. We may save that one for another day. But it can be done.

Running Numbers on the Elevator

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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…

The Odds of Going to a Movie

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For an engineer, while there are some movies on their list, many movies are simply not viewable. Here is an equation to determine whether an engineer will go see a movie.

M = (T * At * L)/(E * R)

Where,

M = the Movie rating, how likely the engineer is to go to this movie

T = Technology rating, how much technology is used to develop the plot (the plot is actually not essential)

At = the amount of Advanced Technology, mainly things that haven’t been invented yet, like phasers and trimogrifiers. These are not simply magical devices, but have some root in science, only somewhat fiction (so, I guess, science fiction)

L = Logic of the story and actions of characters. Characters doing stupid, illogical things are simply not appealing.

E = Emotional rating. How likely is it that a date or significant other will actually start crying like they are watching Downton Abbey?

R = Romance level. More romance, less likely.

One sees that T, At, and L are in the numerator. These are good. The more of them, the better. The E and R are in the denominator. The more of them, the more likely it is that the engineer will be home calculating a better way to entertain the family.

Equilibrium

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For an engineer, equilibrium is something to be attained – at home, at work, on travel. Equilibrium means things are equal. At peace. Not changing or frenzied. One equilibrium issue which is always running through my mind in winter is thermal equilibrium of our home.

ΔHeat = 0

Or, put another way,

Heat In = Heat Out

It seems simple enough. The more heat is transferred out of the house, the more the heating unit will need to transfer heat in to the house if equilibrium of the home temperature is to be maintained. I sit there and see the heat transfers take place and plot how I can affect this equation. How can I prevent heat from transferring out of the house, therefore reducing the need for more money being spent to add heat to the other side of the equation.

This is why we insulate our homes, seal the cracks around our windows, and yell at the kids to “Shut the door!”

Equilibrium.

Approaching Holiday

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With the impending holiday of Christmas approaching, the engineer could help optimize for time efficiency and benefit-cost of the present for a person, taken here as a significant other.

For time efficiency,

Te = TC/S  + J

Where:

Te = Time efficiency in gift-buying

TC = Time until Christmas in days

S = Time spent in a store, buying a gift

J = Joy Content of gift for recipient

The Joy Content is derived by a 0 to 10 survey given to the one receiving the gift. Note that the smaller TC, in other words the shorter time to Christmas, the smaller S needs to be, meaning the time spent in the store needs shorter. The goal is to maximize the Te, spending less time in a store, and bring greater Joy to the recipient.

This is the way to approach Christmas shopping.

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