Here’s an image of a contraption. It is basically a long stick hinged at one end and is free to move about the other. At the end of it rests a ball. Near the ball there’s also a cup fastened to the stick. The big stick is lifted up high and is temporarily supported by a small stick.
Now, what do you think would happen when the temporary support is removed? Normally, it would be very intuitive to think that the cup and the ball would fall at the same speed. In other words, nothing fascinating would happen. Both would fall and the ball would roll away…no?
However, something very unexpected happens when the support is removed. Something that, in a jiffy demonstrates some very important concepts of physics like centre of mass, torque and acceleration.
The big wooden stick (with the fastened cup) falls and it falls faster than the ball. Actually it falls and also rotates. As a result of the swing, the cup comes under the ball just before ball reaches it and the ball ends up inside it.
Under the influence of the same gravitational force, irrespective of the mass, the cup and the ball must have fallen at the same rate, as predicted by Galileo? What really happens? The video explains…
For years the phrase “cake cutting” has conjured up just one image in my brain – A triangular section of the cake. This way of cutting a cake is so normal that even the tools (especially the spatula) that are made for cake cutting are made in a way that’d work with best when you are making that traditional triangular cut. Turns out, this method of cutting a cake which we’ve all know for years is totally wrong.
Why is it wrong?
It’s wrong mostly for mathematical loners. People who, on their birthday, have no one around to share the cake with, and cannot finish off the whole cake. For them and the ones who have to store the cake after cutting it, are extremely careful about how moist the edges remain when they next eat it, this right way to cut a cake might be of great importance.
The way we’ve always know is “wrong” because when you cut off, say a single section of the cake and decide to store the larger piece in the fridge, some internal part of the cake remains exposed and it dries off. So, the next time you cut off a piece near the area where you started, you’d get a freshly cut moist wall of cake on one side, and a repulsively hard dried up wall on the other. That, some think, is extremely unpleasant.
What’s the Right way?
About 100 years back, a brilliant Polymmath (and a mathematician), Sir Francis Galton, faced a similar annoyance. So, instead of cursing others for having invented an absurdly inefficient way to cut a cake, he decided to develop his own. He ended up developing a very simple and efficient cut which helped him keep the cake wall relatively moist. Here’s how the cut works. (Cut along the dotted line)
Describing his new way of cutting cakes, he got an article published in the Nature magazine (dated December 20th, 1906). “Cutting a Round Cake on Scientific Principles”
Alex Bellos from the Numberphiles describes it in a video below:
What this grossly obese man did in the year 1965 is probably one of the most stupidest things you could emulate tolose weight. Doctors, and I would advice you totally against it. Yet, I felt that it’s good to know a stupid thing once in a while, in order to avoid it (maybe). Luckily, the man who did it, ended up fine and also lost several dozens of kilograms in the process. Here’s what happened…
By the end of his fast, the man had lost around 126 kg of weight. That’s about 61% of his initial body weight! For the whole time, his body had used up the stored fat to power him. It was incredibly lucky for him that he did not face any adverse conditions while he was doing this. A slightly gross thing to know is that, since he wasn’t eating anything, he felt a need to use the bathroom only once in 40-50 days.
The Science of it
Normally if you don’t eat for a couple of hours, the human body is able to extract energy from the glucose in your bloodstream and liver. After about 8 hours, you no longer have any of the glucose left in your body.
Once the glucose is finished, the body starts burning a bunch off glucose molecules stuck together – known as glycogen, stored in muscles and liver. This source finishes off in about 2 days’ time. After that the body starts breaking down muscles. But that can be avoided by taking up a few defined exercise routines.
Next the body starts using up fat molecules into glycerol and free fatty acids. Everything in your body can run from this good source of energy. And that is how the fat gets lost. Surely, you don’t want to do that because you’ll end up sick, weak, depressed and cranky. You might even die if you try this.
Here’s an account of a person, who recently tried fasting for 11 months. Below is an image of what the fast did to him. Yes, he’s the same person (with a gap of 11 months of course). It was clearly a very bad experience. [Link]
Please note, in the heading I said, a fun way to multiply numbers, not necessarily a quick way. Widely touted as an “amazingly quick Japanese method to multiply”, I think firstly, it really is not a very quick method. Secondly, I couldn’t find any sources confirming that it is a method developed by the Japanese. In fact, I’m not even sure if there’s anything Japanese about it. Nevertheless, the method sure is fun and should work great for people who don’t remember the multiplication tables well.
Another great thing about it is that it is a multiplication problem turned into a visual counting problem. Since multiplication exercises don’t really make kids happy, they’d definitely love to count intersections instead (multiplication disguised intelligently).
Of course the counting can be used for single digit numbers too, but that won’t be too useful. For slightly more complex problems involving 2 digits like 32 X 42, it could be a life saver. It’s a fairly simple 3-step process. Here’s how you do 32 X 42 with it…
Step 1: The best way to go about it is by starting from the top left. First, you draw the 3 lines for the 3 of the number 32. And then you make 2 lines for the number 2, as shown.
Step 2: Next make 4 lines and 2 lines intersecting the previously made lines as shown. Clearly, 4 lines for the 4 of 42 and 2 lines for the units place of 42.
Step 3: Count the number of intersections in the far left (a), centre (b), and the far right (c). (a), (b) and (c) are 12, 14 and 4 respectively, for this problem.
The 1 from 14 gets carried to the number just at the right of it – 12 of (a), and (a) becomes 13. A similar carrying of the ten’s place to the immediate right column happens if there are any 2 digit numbers. So you are left with 13, 4 and 4 now. 1344 is the answer to 32 X 42.
This can be done for 3 digits too and more…
If there’s a zero, you could make a line and not count any intersections with it. As it has been shown in the video below…
Please hit like if you learnt something from this article.
Here’s the thing. Go to ToneDeafTest.com and take that little test they have on their homepage. That is what you need to do first. Stop reading further if you haven’t done it yet.
Assuming you did what I asked you to do…
If you did well in the test (with a few silly mistakes which can be ignored), you’ll probably understand better what I’m talking about in the following article. Otherwise, you might miss the point.
Nevertheless, there is still a chance that you’d understand even if you are tone deaf. I’m not sure because I’m certain not tone deaf and it’s impossible for me to understand the subjective experiences of tone deaf people (I can boast that the first time I took it, I got a perfect score in that test). Anyway, that test is a fun thing to do. You’ll at least learn something about yourself.
The endless stairs and the endless tone
Everyone knows the endless stairs (in the picture below). Now, you’d think why is the author talking about a visual illusion just after he told us to take an auditory test. That is because the popular visual illusion helps you to relate better to a relatively lesser known auditory illusion.
If you start going up on the endless stairs, you always keep moving up. Even after you come back to the same place, you still keep going up. An impossibility. But it’s something that fools your eyes. The same thing happens if you start going down the stairs.
A similar thing can happen with tones. Listen to the following (continuous?) note sweep.
It sounds like a tone that is continuously going down, endlessly. Only, it isn’t. It’s actually a much smaller looped sound that starts from a high point and then goes down. These little loops have been placed one after the other. If you do not carefully listen to it, you’ll never find the exact point at which one loop ends and the next loop starts. You’ll always interpret it as a continuously going down sound. Just like the continuously going down stairs. This is called the Shepard tone.
This works for discreet notes also. Listen to this endless mario stairs video to get an idea how it works for individual notes (not sweeps).
Why?
Notes are not simple frequencies. A single note is usually composed of several other frequencies. To not overwhelm us with data, the brain puts all these frequencies together and we hear a single sound (note).
Also, our brains like continuity. So, it cherry picks the frequencies from the loop’s notes that makes us hear a continuous sweep. This is the reason we hear no individual loops. Bah! I’m not very good at explaining this. So, here goes the Vsauce video which explains it better. Note that the arrows in the video are the frequencies I was talking about…
In a wonderful paper titled “Unskilled and Unaware of it“, two social psychologists from Cornell University, Justin Kruger and David Dunning share an incredibly funny story of Mr. McArthur Wheeler. Although it is funny, the story actually beautifully demonstrates an excellent concept – a kind of cognitive bias (discussed later in the post). Here is the story:
The Story of Mr. McArthur Wheeler
On one fine morning in Pittsburgh (PA), in the year 1995, a man aged 44, known by the name McArthur Wheeler decided to rob a bank. Since he thought he knew a lot about a peculiar chemical property of lemon juice, he decided to smear the juice on his face before executing his plan to rob the bank.
His logic – As lemon juice can be used to write invisible letters that become visible only when the letter is held close to a heat source, he thought, the same thing would work on his face too. By smearing lemon juice all over his face, he thought that his face would become invisible to the security cameras at the bank. He did not just think that, he was pretty confident about this. He even checked his “trick” by taking a selfie with a polaroid camera. I’m not sure if the film was defective, or the camera wasn’t operated properly, but the camera did give him a blank image. The blank image made him absolutely sure that this trick would work. Or he would not have ever dared to rob a bank with lemon juice on his face.
That day, he went on and robbed not one, but two saving banks in Pittsburgh. A few hours after he had done his job, the police got their hands on the surveillance tape and decided to play it on the 11 O’Clock news. An hour later, an informant identified McArthur in the news video and contacted the police with the man’s name. McArthur got arrested on the same day. Ironically, the same surveillance cameras that he was confident would not be able to capture his face, got him behind the bars. During his interaction with the police, he was incredulous on how his ignorance had failed him.
The Dunning and Kruger effect
Both the psychologists Dunning and Kruger got story of Mr. McArthur. They decided to study it more deeply. The psychologists were interested to study about the utter confidence of Wheeler that made him believe he’d be able to foil the security cameras with lemon juice on his face. He had the confidence, but he clearly wasn’t competent enough…Why was he so sure he’d succeed?
Their study finally demonstrated that the less competent an individual is at a specific task, the more likely they are to inflate their self-appraised competence in relationship to that task. This phenomenon is today known as the Dunning–Kruger effect.
As Charles Darwin rightly said:
Ignorance more frequently begets confidence than does knowledge.
At zero experience in the x axis it’s not “no nothing”. It’s *Know nothing (There’s a spelling mistake in the image) – ‘On Finch’ mentioned this in comments below.
Indian Idol contestants and the Dunning Kruger Effect
This effect is clearly observed during the auditions of reality shows like Indian idol (etc). The auditions are usually thronged by a variety of good and bad singers. The ones who are bad at it, never realize their incompetence and yet are genuinely disappointed when they get rejected. Often times, they resort to noisy quarrels too.
If you’ve observed carefully, people who aren’t very good at humour or sarcasm often tell poor jokes and expect people around them to laugh hard. But when people don’t laugh, they seem genuinely shocked. It is incredible to see them totally unaware of how bad they are at it.
At every place, it is a common tendency of the least skilled people to have an inflated sense of self-competency.
Ignorance sure is a dangerous thing.
Did you like this article?
Every day I send out a newsletter with an un-cut new article and exclusive content for readers. It’s basically my way of keeping in touch with you and letting you know what’s going on. Your information is protected and I never spam.
Donating = Loving
A small donation worth a single cup of coffee from you can be the difference between this website existing or not. If you like this, please consider buying me a cup of coffee:
Let me just not say anything before I make you watch this video today:
In the video, a Nickel ball is heated using a torch and is dropped into a bowl of water. As the hot ball touches water for the first time, it makes a certain “Ping” sound. It enters the water and gets covered in a bubble sort of thing. As it cools and the bubble is lost, that “ping” sound comes back again. The “Ping” repeats several times and is fun to hear a metal ball do that!
So much fun that the good guys on Reddit even made a couple of ringtones out of it. Download the longer one here. And the shorter one for notifications here.
Why does it form a Bubble cover?
This happens because the metal that is dropped into water is extremely hot and makes the water around it vaporize. The vapor formed around the ball acts as an insulator and doesn’t let the water touch the metal ball. This is the same effect that lets dip your hand in molten lead or Liquid Nitrogen without getting harmed by it. The same thing happens when you drop water on a hot pan – it dances.
This effect is called the Leidenfrost effect and I’ve covered it in an article before…
I’m not sure what exactly causes the “Ping” sound. If you know or have any theories, please tell me in the comments below.
CrashCourse in Quenching
Well, if I’d have wished to piss you off with jargon, I’d have said: “You just watched a hot Nickel ball being quenched in water”
Yes, quenching. Quenching is the name for making a hot metal cool very quickly. It is pretty interesting to know why some one would, with great effort, heat a metal, and then choose to drop it in water to cool off!
Cooling a hot piece of metal very quickly makes it extremely hard. So hard, that the same process is used to make the hard edges of swords that don’t get damaged even if they are used to cut metal!
There is so much more I wanted to write about the process, but I feel this isn’t the right place for it. Let me leave it for some other day.
For the last several days, the national average temperature in the US plunged by a several notches when the country was invaded by the bitingly cold polar vortex winds from the arctic, not once, twice. For the second time, the eastern sea board experienced a lot of trouble. So much that the state of Georgia, Alabama, Mississippi, Louisiana, North Carolina and South Carolina declared a state of emergency. People got trapped for hours, hundreds of accidents were reported and schools had to shut down.
Conspiracy theories
Of course with the extremely cold winds came an abnormal amount of snow. And like always, even the seemingly harmless snow spurred a few theorists to spin out conspiracy theories. There were stories going viral that suggested that the crazy amounts of snow was actually “geo-engineered” and was being sent down by the government, stuffed with nano-bots to control the minds of people.
What backed them? The theories were backed with a claim that the material falling down from the sky was not actually snow and something else which did not melt when held against a flame. Videos showing people trying to melt the snowballs using a cigarette lighter went viral. In fact, the snow as it’d be expected to, wasn’t melting, it was collapsing. Like a Styrofoam dipped in acetone, or Styrofoam held against a flame would do, snow was mysteriously disappearing from around the flame. There was no dripping water. Moreover, the concave part of the snow was left with a black charred mark like plastic would!
Busted!
Turns out the “mysterious material” was nothing more than normal snow. The lesser known fact that snow does not melt like we’d expect it to, made people believe in the weird theories.
Yes, snow does not melt like normal ice. I mean it does melt, but it leaves almost no dripping water when the rate of melting is slow. Now, why is that?
Since, snow is porous, it contains several little holes that can suck in the water just like a tissue paper with tiny holes is able to soak in water. This particular process soaking, where tiny solid holes suck liquid, is termed as capillary action and is the same action which enables plants to suck in water from the ground and send it to the higher parts without any motor attached.
The soaking in a snowball happens in real-time. As the water gets melted, it gets soaked instantly, there is no time for the water to drip. This explains the collapsing snow.
The “charred snow” is due to the unburnt carbon left from the fuel of the lighter, not because it is made of plastic. Astronomer and science writer Phil Plait explains it in the video below. [Video]
Suppose, you have a neat pile of a really long chain of beads in a beaker (Newton’s beads) and you give one end of the beads a tug and let it drop on the floor, what do you think will happen?
Steve Mould, a YouTuber, did the same with a 8000 bead chain. It was 50 meter long chain of beads placed neatly in a container. Then, after he tugged it out and let it drop, the chain mysteriously formed an arc above the beaker and continued to self-siphon away till the end. Just like a water-siphon.
To figure out what was actually going on here and to understand the exact physics of it, a group of physicists recorded the “gravitational defiance” using a hi-speed camera. Here is a five-minute long video-bliss, brought to you by the Earth Unplugged channel. [video]
As Steve explains, it is like a tug-of war between the outer chain and the inner chain. The inner chain has to keep up with the fast-moving outer chain. As a result, it [the inner chain] goes up fast. It builds up momentum and is unable to stop itself. So, it ends up forming that arc while it is trying to slow down and change direction.
