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by craigshieldsPosted on Posted in Renewables - Politics

Two comments on the meme here:

a) It’s next to impossible to know whether or not 1970s rocker Alice Cooper actually said this.  Today, it’s common for the MAGA crowd to fabricate stories about celebrities who are known to be kind and thoughtful people who, for instance, “refuse to work with Disney because the organization is ‘woke.'”  Idiots believe this, and we live among them. It’s pathetic, but true.

b) Fortunately for us all, we Americans enjoy the protection of most (but not all) forms of speech under the First Amendment to our constitution. Yes, there are people who, erroneously, believe that Trump’s inciting the January 6th insurrection or lying about the honor of the judges presiding over his prosecution of the 88 felonies he is alleged to have committed are similarly protected.

But here, we have popular people who simply want to express their views.  These people include billionaires, star athletes, actors, and musicians.  If you have a problem with that, you really have no idea what First Amendment means.

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by craigshieldsPosted on Posted in Renewables - Politics

Two old friends are having a discussion about Benjamin Netanyahu and his level of intelligence; one says he’s “stupid,” and the other disagrees.

Now, I don’t follow Israeli politics as closely as either of these two, but here’s my take on the matter: Insofar as he’s a demagogue, and an extremely effective one at that, we need to grant that he possesses intelligence along a certain dimension that is sufficient to enable him to figure out, with fabulous precision, how to address his audience and control their behavior at the polls.

It’s unclear if he’s capable of solving differential equations, speaking half a dozen languages, or following the advancements in particle physics, but that’s completely irrelevant.  The only matter at play here is his love of power, and his capacity to manipulate “common” people, using rhetoric to stir up the passions of the masses so as to push him into power and keep him there.

Here in the U.S., we frequently have the same conversation about Trump.  Those outside his base see him as unintelligent, a conclusion we draw from his childish use of the language, and his total lack of interest in information that would have helped him do his job (Where is Israel? Should COVID patients ingest bleach?)  But again, this is irrelevant, in the same way that characteristics like charisma and height are irrelevant to the success of chess players.
In addition, Trump is clearly a criminal sociopath.  Now, most people don’t think of people like Netanyahu (or Hungary’s Orban or Turkey’s Erdogan) as kind and decent people, but they don’t seem as deeply disturbed as Trump.
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by craigshieldsPosted on Posted in Renewables - Science

Reader Drew Douthit adds this clarification to my post on the drawing here: “Take a Cool Guess—The Fun Quiz on Renewable Energy and Environmental Sustainability. Today’s Topic: Basic Physics”

 

It all depends on vehicle speed….
okay! For 165lbs diver it’s over 67mph!
Note that the cartoon is intentionally misleading for the purposes of humour. It’s drawn as if the diver had no forward velocity, so as soon as he jumps the vehicle will shoot away from underneath him. However, in the real world, at the moment of taking off the diver would have a forward velocity equal to the velocity of the vehicle. So in real world situations the diver could land in the pool.
of a motorcycle passenger going airborne at speed and landing in her seat.
But the situation in the cartoon could happen, if the vehicle was going fast enough and/or there was a strong enough headwind. In this scenario, although the diver starts his dive with forward velocity, the air/wind resistance will reduce that forward velocity and he could miss the pool as the vehicle continues to move with constant velocity.
Let’s try to do the maths. We’ll need to make some estimates and assumptions.
In the picture I’d estimate that **the diving board is about 1 metre high, and about 2 metres long** from the take-off point to the back of the vehicle.
I’ve watched some videos of Olympic platform divers and they don’t tend to gain much height as they take off. Yeah, the guy in the cartoon is on a springboard, but it’s not a very long springboard and statistically he’s unlikely to be an Olympic class diver. Let’s assume he gets about **1 metre above the board** at the peak of his dive.
We can easily use the Newtonian equations of motion (**s=½at^(2)** etc) to calculate how long he’s in the air. With a = -9.8 m/s^2 we find that jumping 1 m takes 0.45 s and then falling 2 m takes 0.64 s, for a **total air time of 1.09 s**.
When we’re looking at the horizontal motion, we can use the vehicle as an inertial reference frame. So we have the diver starting off stationary, and then when he jumps he’s subject to a horizontal force due to the air. Note that we won’t be able to distinguish between vehicle speed and wind speed: jumping off a stationary vehicle into a 50 km/h wind is the same as jumping off a vehicle moving at 50 km/h through still air. Anyway the question is what wind speed does the diver have to experience, for it to move him 2 m horizontally, from a standing start, in 1.09 s. If we assume that he’s subjected to a constant acceleration, Newton’s equations tell us that the **acceleration must be 3.36 m/s^(2)**.
Newton tells us that **F = ma**, and the force of air resistance is **F = ½CpAv^(2)**, where C is the drag coefficient, A is the cross sectional area, and p is the density of the air. So we can set these two expressions equal to one another and then rearrange to get **v = √(2ma/CpA)**.
We calculated a = 3.36 m/s^(2), we’ll assume the **mass of the diver is m = 75 kg**, and we know that the density of air (at sea level and 15°C, the International Standard Atmosphere) is p = 1.225 kg/m^(3). Though having said that, if the air temperature were 15°C, I don’t think we’d be going swimming and diving. Let’s assume the air temperature is 25°C, in which case the **air density is p = 1.168 kg/m^(3)**. So we plug all these values into v = √(2ma/CpA) and we have **v = √(431.87/CA) m/s**.
Now we need values for the drag coefficient C and the diver’s cross sectional area A. Fortunately I found [this source](https://phys.libretexts.org/…/6.07%3A_Drag_Force_and…) which states that a human skydiver has a cross sectional area of about 0.18 m^2 and a drag coefficient of about 0.7 in the head down position, and a cross sectional area of about 0.70 m^2 and a drag coefficient of about 1.0 in the spread eagle position.
Now this is a bit awkward because obviously a diver changes his orientation, and hence his cross sectional area and drag coefficient, during the course of his dive. But, looking at the cartoon, in the second panel the diver hasn’t really had enough time to pivot into a head down position. He looks like he’s been pretty close to the spread eagle position throughout. So I’m going to take **A = 0.70 m^2 and C = 1.0**. That also means I don’t need to worry too much about that assumption of constant acceleration.
And here’s our answer! We have v = √(431.87/CA) = 24.8 m/s which is **89 km/h or 56 mph**. As noted previously, that’s the speed of the air into which the diver is jumping. It could be a vehicle moving at 89 km/h in still air, or a stationary vehicle in an 89 km/h headwind, or a vehicle moving at 120 km/h with a 31 km/h tailwind, or any other combination that adds up to 89 km/h.
**EDIT:** If you’d like to calculate your own answer, you’ll need values for the following parameters:
* m = mass of diver
* l = length of springboard
* g = gravitational acceleration
* C = diver’s drag coefficient
* p = density of air
* A = diver’s cross sectional area
* j = height of diver’s jump above board
* h = height of springboard above vehicle
and then plug them into the following equation:
**v = √(2mlg/CpA) / ( √j + √(j+h) )**
Good luck trying that with anything other than SI units!
**EDIT 2:** It just occurred to me that I implicitly assumed the diver would jump slightly sideways, so that he wouldn’t land on the springboard as he came down. That’s perhaps not realistic. But if he jumped straight up, the situation is that he has to travel the 2 metres back towards the end of the vehicle before he comes back down to the level of the springboard. This is easily achieved by setting **h=0** in all the calculations above. We get v = 30.0 m/s which is **108 km/h or 67 mph**.
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by craigshieldsPosted on Posted in Renewables - Science

I don’t believe this claim about the cause of atheism.

True, hypocritical Christians are a huge turn-off to most of the world’s population; this has been the case for centuries.

But most atheists make their choices based on their perception that science and reason form a stronger belief system than faith in an invisible friend in the sky.

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by craigshieldsPosted on Posted in Renewables - Science

In response to what Neil deGrasse Tyson says here, all I can say is, “I hope so, but I don’t see too much evidence that this is where we’re going.”

How much science and other forms of clear-headedness are we applying to ending the humanitarian crisis in Gaza and elsewhere around the world?  To climate change mitigation? To preventing the death of U.S. democracy? To optimizing our approach at the southern border?

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by craigshieldsPosted on Posted in Renewables - Politics

My father was a B-17 bomber pilot in the European theater of WW2, who, by 1944, had flown with his 10-man crew, 29 successful missions destroying Nazi crude oil refineries.  They were shot down on November 25 of that year, on the return trip from what would have been their 30th. Still over Germany, about 10 miles short of the French border and having lost three of their four engines, they had run out of luck.

Dad and his men had no option but to bail out, parachute to the ground, and hope for the best.  They did, however, have a decision to make, and an important one at that.  They had the choice to remain in uniform, making them a cinch to identify (and capture) as allied troops.  Alternatively, they could change into civilian clothes, making it far easier for them to make their way on foot into neighboring France without being noticed by the enemy.

There was a considerable risk, however.  Choosing to remain in uniform prohibited the Germans, under international law, from gunning them down on sight; if captured, they would be made POWs, treated humanely, and released unharmed at the end of the war.  On the other hand, changing clothes enabled the Germans to treat them as spies and execute them by firing squad.

This tale is only partially a tribute to my father. It’s more an illustration of how common Americans who become soldiers in wartime face momentous decisions that former presidents do not.  If you’re lucky enough to be Donald Trump, it appears that you can conduct yourself with immunity, and thus spying, in his case, leaking top secret military documents, doesn’t even lead to criminal prosecution, let alone an array of bullets through your heart.

 

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by craigshieldsPosted on Posted in Renewables - Politics

It’s kind of funny that these people consider themselves “conservatives,” while there is essentially zero that they wish to conserve.

Most obviously, they want an immediate end to the rule of law in the United States; they want a democracy which no one is above the law–except the U.S. president.

 

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by craigshieldsPosted on Posted in Renewables - Science

People have been talking about this subject ever since theoretical physics became a thing around the turn of the 20th Century, and, simultaneously, we had the onset of the “philosophy of science.”

IMO, there are no distinct answers here, other than the basic: if a statement can’t be subjected to an experiment that could potentially disprove it, it can’t be considered scientific.

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by craigshieldsPosted on Posted in Renewables - Politics

Apparently, it’s news when working class America support a Democrat for U.S. president, even when the Republican candidate’s track record while in office featured lavish tax breaks ….. for corporations and billionaires.

The decline of quality in public schooling and the deep-seated frustration of the common American seem to have combined to draw these voters toward Trump, who is a true expert at fanning the flames of anger among the poorly educated.

It’s possible that Biden has, at least in part, turned this around.  All the disinformation in the world can’t change the fact that the current president has been very good for the welfare of “the little guy.” It’s nice to see that this is being recognized.

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by craigshieldsPosted on Posted in Renewables - Politics

We all know that Elon Musk is no fan of wokeism.  But does what he says here make any sense?

Most people would agree that there is nothing funny about being considerate of other people’s feelings, or working to build a fair and just society.

If I wrote that no one laughs at oranges because they’re not tomatoes, would readers find that meaningful, or would they think that perhaps Craig has lost a step?

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