Category: Physics

[Video] Making a Perfect Ice Sphere

By Anupum Pant

Ice cubes are too mainstream. Moreover, considering the greater surface area cubes have (as compared to spheres), they melt too quickly. Who’d want that in their drink?

So, here’s a device that can make ice spheres using just gravity, in under a minute.

The simple aluminium mold isn’t powered by any heat engine. It simply works by pressing the ice cube and conducting heat really fast. Also, using the perfect amount of pressure so that it doesn’t crack the cube. It works because aluminium has a high thermal conductivity. 

The end result is a perfect ice sphere made out of an ice cube in under a minute. No heating involved.

Galileo’s Paradox

By Anupum Pant

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.

galileo paradox

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…

Double Pendulum and Why We Can Never Predict Weather

By Anupum Pant

A single weight, if suspended from the ceiling, forms a pendulum – A simple device whose position at any point in the future can be predicted fairly easily if the initial conditions are known.

Now, if another pendulum is attached to the bottom of this first pendulum, preferably using a rod (not a string), and is then given a good amount of initial energy, things move from a simple single pendulum to a very complicated two pendulum system.

The system turns so chaotic that it is impossible to make two of such exactly same systems, forget keeping them synchronised. Even if every mass and ever little distance is carefully calculated and two such systems are constructed, it would be impossible to drop them from the same height and see them move in the exactly same manner.

That is because even if they are really dropped from the same position, they’d in reality have a very tiny difference in some parameter, which would eventually become so huge that the two systems would soon go out of sync. Initially they might really seem like they are moving in a synchronized motion, but that doesn’t stay for too long.

This is also the reason why we’ll never be able to predict the weather perfectly. Nikola explains…

Gravity Explained

By Anupum Pant

I’m always amazed by how teachers all around the world come up with fantastic ideas to make science easier for kids. A couple of months back we saw a video of Dan Burns using a trampoline to explain the space-time warping at a Physics Teacher SOS workshop in Los Gatos High School. In fact there is even a place on the web where you can learn it to do yourself [here].

Another explanation which came around much later just takes the cake. EdwardCurrent uses a “space-time stretcher” to demonstrate how gravity, well, stretches the space-time fabric. Moreover, the material he uses to construct this teaching aid comes mostly amongst all the old stuff lying in his garage.

Continue reading Gravity Explained

Shot Towers

By Anupum Pant

The way of making lead musket balls before 1782 involved a lengthy process. And if you had a huge army, then you were in for a massive task. To make each ball:

  • A chunk of lead was melted in a crucible
  • Poured into a mould
  • It was let to stand to solidify
  • The mould was broken
  • Final finishing of each ball was done
  • and each ball was checked for roundness by rolling it on an inclined plane

Then everything changed in the year 1782, when a plumber from Bristol William Watts, got this seemingly simple idea – Drop molten lead from a long tower and let the surface tension do the work.

He got this idea by observing raindrops, which formed perfect spheres while they were free-falling. Before telling anyone about it, he tried implementing his idea. He dropped molten lead into a bath of water from the tower of his local church. It worked perfectly.

He did a couple of other experiments at home and finally patented his idea by the end of the same year. It wasn’t long until shot towers started sprouting all over the world. William made a good fortune out of this.

A shot tower is a long hollow building, like a light house, which has the machinery to melt lead at the top point. The molten lead is dropped into the long hollow shaft through sieves, and the bottom part of the building has a bath of water to catch lead balls. The free falling lead turns into a sphere due to surface tension and solidifies in air due to flowing air. After shots are made, they are lifted from the water and checked for roundness by making them roll on an inclined plane. Defective ones are sent back to the top.

The tallest shot tower ever built was 263 meters long and was constructed in the year 1882. It still stands in the Melbourne suburb of Clifton Hill in Australia. There are several others around the world which are still standing. While many others have either been destroyed by men or nature.

via [PSSA]

Best Explanation of Quantum Entanglement

By Anupum Pant

I don’t know a lot about Quantum entanglement, but I still think it is very interesting. So much that a PC game which contained of this concept, immediately landed on the list of my most favourite games. Yet, it sure is a tough thing to get into your head.

Fear not. Associate Professor Andrea Morello of  University of New South Wales (UNSW) is here to explain it to you, in this video which people have started calling – “The best explanation of quantum entanglement so far”. I have to admit it, I am still not sure if I really understand what the professor tries to explain in the best explanation ever video.

In very simple words entanglement works like this. If two objects are entangled with each other, and if you separate them by any distance (even place them at the opposite ends of the universe), then they’d still remain connected very peculiarly. Entangled particles even separated by a massive distance would still be connected – as in, whatever you did to one of the particles would instantly happen to the other particle at the other end.

The instantaneous reflection of changes done on the first particle to the other particle happened faster than light. And Einstein didn’t like that, he called it “spooky action at a distance”. Tom me, this video explains it better…

Turning Lead to Gold

By Anupum Pant

Hunt for a process to convert a brick of lead into gold was probably the most elusive quest during the olden times when alchemy was around. However, alchemists, who were mostly dismissed as pseudoscientific quacks, actually did some good ground work to make their dream of turning lead to gold into a reality.

And then came the 20th century, when transmutation of one element to another became fairly common. In fact nuclear reactors started working on the same principle. So, besides breaking of uranium atoms and combining of hydrogen atoms to form helium, did it actually become possible to transmute lead into gold using the same process?

Sure it did. Today it is totally possible to make lead (Atomic number 82) release 3 protons to turn into gold (Atomic number 79). Not just in theory, people have actually done it successfully in laboratories. For one, Glenn Seaborg is said to have done it in the year 1951.

To do this, you’d need a particle accelerator. And if you plan to use it as a get rich quick scheme, then you are in for a bad news. Transmuting lead to gold in a laboratory consumes massive amounts of energy, even if you have to do it in extremely minute volumes. So much that the price of doing it exceeds the price of gold by a very big amount. Also, only a very minute volume of gold comes out this way.

To make a single ounce of gold this, it would cost you one quadrillion dollars. You could just buy the same amount for $1300 instead.

Chladni Figures

By Anupum Pant

If you take a surface, membrane with a layer of loose particles or certain liquids on it, you’ll see that these particles get arranged in beautiful patterns if the membrane is made to vibrate with varying frequencies.

This phenomenon has been known for a long time now, probably since the time when early human tribes used to put grains of sand on drums made of taut animal skin. Since then Leonardo Da Vinci and Galileo Galilei have been known to have observed this phenomenon by hitting or scraping a surface covered with visible particles and .

Later, with information gleaned from Galileo’s and Leonardo’s notes, in the year 1680, Robert Hooke, English scientist from the Oxford University, devised a simple equipment which demonstrated this effect much clearly. He made a glass plate covered with flour to vibrate with the help of a violin bow. And observed beautiful patterns.

Much later, Ernst Chladni explained these figures using mathematics, spread it all across Europe and made a lasting impression on The French Academy of Sciences. These patterns thus came to be known as Chladni figures.

Brusspup, a YouTube channel known for it’s amazing videos demonstrates these Chladni figures on video.

Today, this study, which makes sound and vibration visible to the naked eye, is called Cymatics.

A Few Amusing Physics Phenomena

By Anupum Pant

Veritasium has always amused us with very interesting physics phenomena over the years. And now, as always, the channel has asked its users to send their answers to these 5 interesting physics mystery.  Here have a look at them…

Do leave a reply on his channel if you think you know why these happen.

For all of the 5 things, I do have my own theories but I’d rather wait till the next week when Derek will release the solution video. I do not want to publish my haphazard theories, which might be wrong.

However, I’m quite sure about one thing. Why does cereal get attracted by a magnet?

That is mostly because it has iron in it. By iron I mean real iron in its pure form. In fact, you can even extract iron from cereal. The best part is that it is not even difficult. All you need is cereal, a neodymium magnet, water, a bowl and a resealable bag.

The Weissenberg Effect

By Anupum Pant

Remember the time we talked about a boiled egg spinning on a pool of milk? If you don’t then it’s good to know that if you do spin a hard-boiled egg on a pool of milk (or any relatively viscous liquid) the milk mysteriously climbs the side of the egg, reaches the equator, and then sprinkles around beautifully. It’s fun to see it happen. This is something similar…

The thing we see today is called the Weissenberg effect and this is how it works.

You take a spinning rod and put it into a solution of liquid polymer (which is usually very viscous). And when you do that, you see that the liquid polymer magically climbs the walls of the rod.

Some liquids reach a little high and never beyond. While others can climb up really high. The difference in heights to which different liquids can climb to is demonstrated in the following video very clearly. The three liquids used in it are as follows:

  1. Guar gum solution crosslinked with sodium tetraborate
  2. Pancake batter
  3. and Dyed glue crosslinked with sodium tetraborate.

[Read more]

[Video] What Travels Faster Than Light

By Anupum Pant

Like always, another one of those awesome Vsauce videos where Michael explains how darkness and scissor intersections can travel faster than light and still not go against any physics laws. So much to learn! Let me just say nothing today.

P.S there’s a mention of the Dunning Kruger effect and the story of Mr. Mc Arthur Wheeler I covered some time back on the blog.

Lightning Trapped Forever in a Box

By Anupum Pant

On a cloudy and stormy night (or almost all the time, in this part of Venezuela), dark clouds separate charges and are able to put together the right conditions to send off one of the nature’s most powerful forces from the heavens – lightning.

The air break downs and a great amount of static charge gets transferred through the path of least resistance. And a bolt of bright light is seen for a fraction of a second. It lasts for a very little time.

lichtenberg-figureAs it happens too quickly, the exact shape of a lightning bolt is difficult to see. However, a long time back, a German physicist, Georg Christoph Lichtenberg, figured something that could help make the lightning bolt last longer. Or in fact, it could trap the lightning tree-pattern forever in an insulator (eg acrylic or wood etc.). The tree-like figure is called the Litchenberg figure after the person’s name (Georg Christoph Lichtenberg) who first noticed this.

Isn’t it a nice sculpture to have – a block acrylic with a lightning bolt permanently trapped in it! Or may be it could be a great gift for your physicist friend. But, sometimes the litchenberg figure isn’t a desirable thing to have…

People who unfortunately end up getting hit by lightning, sometimes survive to this permanent tree-shaped scar mark (or tattoo) – A permanent litchenberg figure gets printed on their skin. It looks like this.

litchenberg figure on skin

Lower Part of a Wheel Travels Slower

By Anupum Pant

Stick a colourful piece of paper on the side of a rim of a wheel and make the wheel roll away. If you observe carefully you’ll see, whenever the paper is near the ground, it appears clearly. However when the paper is at the top of the wheel, furthest from the ground, the paper appears hazy.

Also if you observe the spokes of a wheel of a moving cart, you’ll see that the spokes at the lower part of the wheel appear clearly. While the spokes of the upper part appear to blend into a single body, as if travelling much faster than the lower part.

It seems, the upper part of the wheel is travelling at a higher speed than the lower part of the wheel. How can that be, when both are physical extensions of a single object?

Yes, in fact the upper part does travel faster than the lower part. This sounds incredible, while it seems very ordinary to others who understand the simple physics of it. The physics involved really is very basic. So basic that I’m sure many reading this are cursing me for writing something so ordinary. But I find it really incredible. And believe me, there still are people who need to know this.

Let’s suppose the wheel moves at a speed of v in the right direction. However that is just the speed of the centre of the wheel. The upper part of the wheel for instance rotates at a speed of, say v, and also translates in the same direction at a speed of v. So, the speeds add up. And the top is travelling at a speed of 2v.

Similarly, at the bottom part of the wheel, the rotation is in the opposite direction (towards the left) and translation is in the right direction. Hence the speeds get cancelled and the lowest part of the wheel is stationary.

rims of a wheel

These are the topmost and bottommost points I’ve discussed here. For all the other points on the rim the rotational speed v gets split into a horizontal and a vertical component. So their speeds vary and lie in between 0 and 2v.

Some call it the cartwheel riddle.

Now, if you already knew that there’s something mind-boggling for you here. There’s another similar thing about wheels which blows my mind. Demonstrated in the video below…

Making Xrays Using a Sticky Tape

By Anupum Pant

It’s been known since the 1950s that peeling a sticky tape can produce great amounts of energy. But it wasn’t until recently (in the year 2009) a few scientists, who also didn’t quite believe what sticky tapes could do, decided to actually test this phenomenon.

Astoundingly, a simple act of peeling an adhesive tape, can produce enough xrays to make a Geiger counter cry like a cricket.

In fact, the xrays produced by peeling off sticky tape at the rate of about 5cm per second inside an evacuated chamber can produce enough xrays that can expose a photographic film – enabling you to take an xray of your finger – as demonstrated by the researchers in the video below.

The video is fairly old, was uploaded in the year 2009 and I somehow have never stumbled upon it. It seems relevant even today. Thanks to ScienceDump for showing me this today.

Imagine, you can take an xray picture of your finger using a simple adhesive tape (peeling off in vacuum of course). Scientists possibly couldn’t have discovered a cheaper source of producing xrays.

The vacuum is needed to let enough charge to accumulate before the medium in between the charges breaks. Had the peeling been done in atmospheric pressure, it would have just produced visible light (lower energy than xrays). You can even try doing that at home. Go to a dark room and try peeling off a sticky tape quickly. Thanks to the effect called triboluminescence, you’ll be able to see a spark of light coming out!

The Leaping Shampoo Trick – Kaye Effect

By Anupum Pant

This is really interesting and I can’t explain why. You’ll have to see it for yourself.

Long time back, researchers at the University of Twente in The Netherlands thought of something very weird. They decided to drop a thin stream of shampoo from a height of about 20 cm, ended up discovering an absurd physical effect and winning great accolades for it – The Kaye effect.

The seemingly weird effect can fairly easily be achieved at home by dropping a thin stream of shampoo on a relatively hard surface. In individual steps, this is what happens when you do it:

  • As the stream gets collected, it forms a little shampoo heap.
  • Amazingly, and counter-intuitively, a secondary stream ejects off the heap.
  • The mythical secondary stream becomes bigger, shoots further.
  • And finally hits the incoming stream – this collapses the Kaye effect.

Of course, everything happens really fast. But, if you look at it on extremely slowed down film, you’d see the individual steps happening one after the other.

True, the secondary stream collapses too quickly, scientists weren’t happy about that either. So, they tried tilting the hard surface slightly to achieve a stabler version. Lo! And they had a stable Kaye effect.

This happens because due to certain physical forces the viscous liquid becomes slightly less viscous temporarily – they call it shear thinning. As a result, it causes a new stream to emerge. May be the same effect could be achieved with other thicker liquids like lava, ketchup, whipped cream, blood, paint, and nail polish. But, then lava is too dangerous, and others (barring blood and paint) seem to be too thick. I’m guessing, dropping thicker ones from a higher place could make this happen.

If you find this interesting,you’d definitely love the egg and milk effect, also the chain of beads defying gravity.

Here, watch it on video.