What is the newest installment of 'Random Thoughts' on Physics Forums?

[dlgoff]

Is that a croquet or a polo match?

Neither. It's going to be a butt kick match. Go Chiefs!

 

[fresh_42]

Neither. It's going to be a butt kick match. Go Chiefs!

Are you watching the same match? It is a rare event if games are decided by only FG.

 

[dlgoff]

Are you watching the same match? It is a rare event if games are decided by only FG.

Well. KC did get a touchdown w/ the extra point since my last post.

 

[dlgoff]

Mahomes is amazing.

 

[fresh_42]

Mahomes is amazing.

That was amazing, too. And hard to believe.

 

[fresh_42]

Looks as if FG do decide games.

 

[dlgoff]

Looks as if FG do decide games.

Indeed. Heck of a game. 45 yard FG. Dang.

 

[WWGD]

Getting fit is contagious! Three guys at work are back on their programs because I started back on mine.

We have great facilities where I live. But through work we get a free membership at the local YMCA, which has amazing equipment. You wear an RFID tag like a watch which each machine reads. The machine then automatically sets your weight, with one weight set while extending, and a different weight set while retracting! And it automatically increases your weights over time. How cool is that!!!!

I like using our gym because it's convenient and reasonably equipped. I just throw on my sweats and walk to the gym in 5 minutes. No driving or locker room or crowds. And I almost always have it all to myself. But I have to admit that the stuff at the Y is very cool!

I personally don't use BMI. It doesn't take into account people who work out and have increased muscle mass. I actually gained back all the weight I lost ten years ago. But I was two pant sizes smaller than before. The difference is the amount of muscle added the first round! But the BMI would suggest that there was no difference.

I don't own a scale either. My belt size tells me all I need to know.

You know, Russians used to have this thing , not sure the name, a device attached that would send electricity through your body, mimmicking, or at least trying to , the effects of exercise on muscles, without any actual movement .

 

[Tom.G]

There are similar units available in the USA called TENS units (transcutaneous electrical nerve stimulation). They are sold for use as pain relief and seem to be a lower-power version of the muscle stimulators.

Here is an article at the Cleveland Clinic:
https://my.clevelandclinic.org/heal...nscutaneous-electrical-nerve-stimulation-tens

(above, and seller links, found with:
https://www.google.com/search?q="TENS"+therapy)

 

[Ivan Seeking]

Today I was reminded of an experiment I witnessed when I was about age ten or even a bit younger. Color TVs were out but most people still had black and white sets. Ours was still black and white. A local TV station ran an experiment to see if they could produce color on black and white sets. It was only many years later that I realized what I had seen.

I don't know the proper name for the effect, but I've seen it demonstrated in a science museum. There was a wheel with black and white squares along the circumference. As the wheel begins the spin, the black and white squares begin to look green.

That is what the TV station had tried. They flickered the color of areas of the screen from black to white to black repeatedly and produced the color green. I think they were trying for other colors, but we only saw green. I never did understand what I had seen until about 30 years later when I was at the museum. I suddenly remembered that test and how cool it was. And then AHAH! THAT'S what they were doing.

 

[Ivan Seeking]

Brain teaser: If you are driving with a helium balloon in your car and hit the accelerator, which way does the balloon go and why.

 

[jack action]

Brain teaser: If you are driving with a helium balloon in your car and hit the accelerator, which way does the balloon go and why.

With an air-filled balloon, the balloon will go backward, like any normal object. But with a helium-filled balloon, it will go forward during acceleration.

Why? Because of Zephaniah 1:8 :

And it shall come to pass in the day of the LORD'S sacrifice, that I will punish the princes, and the king's children, and all such as are clothed with strange apparel.

It is clear that God hates people with strange apparel. And who wears strange apparel? Clowns. And what do clowns love? Helium-filled balloons. So God hates helium-filled balloons.

And that is why you should never trust helium-filled balloons.

Context: This is a real argument I read somewhere on a Neo-Christian forum, years ago, that was refuting a physics experiment involving a balloon whose result did not agree with what they were trying to prove. I love it so much and I always wanted to use it somewhere. Thank you for this opportunity!

 

[WWGD]

I believe it's now Zephania 1:8: + $2.99 S&H, btw.

 

[Ivan Seeking]

With an air-filled balloon, the balloon will go backward, like any normal object. But with a helium-filled balloon, it will go forward during acceleration.

Why? Because of Zephaniah 1:8 :

It is clear that God hates people with strange apparel. And who wears strange apparel? Clowns. And what do clowns love? Helium-filled balloons. So God hates helium-filled balloons.

And that is why you should never trust helium-filled balloons.

Context: This is a real argument I read somewhere on a Neo-Christian forum, years ago, that was refuting a physics experiment involving a balloon whose result did not agree with what they were trying to prove. I love it so much and I always wanted to use it somewhere. Thank you for this opportunity!

So you don't know why.

 

[Swamp Thing]

So you don't know why.

TL;DR : YDK

 

[Ivan Seeking]

TL;DR : YDK

So you don't know.

 

[jack action]

So you don't know why.

I always do - like every first poster on PF - a thorough web search: https://www.youtube.com/results?search_query=car+balloon+acceleration

"Knowing" is soooo 20th century!

 

[Ivan Seeking]

I always do - like every first poster on PF - a thorough web search: https://www.youtube.com/results?search_query=car+balloon+acceleration

"Knowing" is soooo 20th century!

It wasn't an appeal to magic knowledge or search skills. It is a fun little mental exercise for those who don't already know the answer.

 

[Ibix]

Brain teaser: If you are driving with a helium balloon in your car and hit the accelerator, which way does the balloon go and why.

I saw somebody on the bus once with a helium balloon. I spent the whole journey watching it doing its thing with my physics brain going "Yeah, totally normal" and my common sense brain going "Argh! Argh! Witchcraft!" It was an interesting clash.

 

[Ivan Seeking]

I saw somebody on the bus once with a helium balloon. I spent the whole journey watching it doing its thing with my physics brain going "Yeah, totally normal" and my common sense brain going "Argh! Argh! Witchcraft!" It was an interesting clash.

The one that completely violates my expectation instinctively, is the following. It is simple math but intuitively a non-compute for me.

Wrap a cord tightly around the earth at the equator [ignore all the practical issues]. Now add one foot to the length of the cord. What is the uniform gap formed between the cord and the earth if the cord is now pulled tight?

What is the radius of a circle having a one-foot circumference?

Too funny! Once I see a mathematical answer it usually makes perfect sense in the real world. But this one not so much.

 

[Ibix]

Too funny! Once I see a mathematical answer it usually makes perfect sense in the real world. But this one not so much.

You mean because the answer is about 4.8cm, independent of the radius of the Earth? You wrap a string around anything circular (the Earth, the Moon, the Leaning Tower of Pisa, a toilet roll), add a foot to the length of the string and you'll have a 4.8cm radial gap between your circular thing and your expanded circular string. Yeah, I agree it's one where you intuitively expect the gap to decrease as the size of the circular thing increases.

 

[Mayhem]

The most reason to pay attention in ODE/PDE classes is to know if your lecturer means t when he writes x and vice versa.
The rigor of a mathematician's reasoning is inversely related to the rigor of their handwriting.

 

[Ivan Seeking]

You mean because the answer is about 4.8cm, independent of the radius of the Earth? You wrap a string around anything circular (the Earth, the Moon, the Leaning Tower of Pisa, a toilet roll), add a foot to the length of the string and you'll have a 4.8cm radial gap between your circular thing and your expanded circular string. Yeah, I agree it's one where you intuitively expect the gap to decrease as the size of the circular thing increases.

It always seemed like there should be a way to view the problem intuitively where it becomes obvious that the radius of C = 1 is simply added to the C_x radius. But I don't see it.
.

 

[Ivan Seeking]

My favorite mind tweak from the world of classical physics, comes from the calculation for the retarded potential of a charge in motion. What is so strange is that even though everything is derived using the [delayed by the speed of light] retarded potential, which comes from where the charge was a moment ago, the electric field vector for an observer, points to or from where the charge actually is now [if the acceleration is 0...]

https://people.nscl.msu.edu/~witek/Classes/PHY432/Potentials and Fields/Potentials2.pdf

I realize there are problems with the conservation laws if this wasn't true, but it was never clear to me intuitively why we get such an elegant solution.

 

[pinball1970]

One is heavier than the other. Then I get stuck!

The one that completely violates my expectation instinctively, is the following. It is simple math but intuitively a non-compute for me.

Wrap a cord tightly around the earth at the equator [ignore all the practical issues]. Now add one foot to the length of the cord. What is the uniform gap formed between the cord and the earth if the cord is now pulled tight?

What is the radius of a circle having a one-foot circumference?

Too funny! Once I see a mathematical answer it usually makes perfect sense in the real world. But this one not so much.

 

[Ivan Seeking]

One is heavier than the other. Then I get stuck!

I'm not sure what you mean. Are you referring to the balloon problem?

 

[pinball1970]

I'm not sure what you mean. Are you referring to the balloon problem?

Yes. I had to watch the YouTube explanation.

 

[Mayhem]

The Li-ion battery on my main laptop is pregnant and my backup PC sounds like a Geiger counter riding a motor cycle.
Great start to my thesis writing!

 

[Ivan Seeking]

I had forgotten about this! Our names [my ex and I] went on a CD sent to Mars on one of the Rovers.

 

[Borg]

My wife and I have our names on Perseverance. It's pretty interesting to think about how there will be a record of us on Mars for probably a very long time.