Tag: speed

Estimating the Distance of a Lightning Strike

By Anupum Pant

Everyone who’s studied basic science at school knows that light travels much much faster than sound. Light can travel about 300,000 km in a single second. Sound, in the same time would cover about 0.3 km. That’s a huge difference.

Considering that, it is fairly easy to calculate how far a lightning strike happens by measuring the time it takes the sound to reach you after you see the lightning. In that case, taking into account the enormous speed of light, you assume that the light instantly reaches you and you just count the seconds it takes for the sound to be heard at the place you are.

Then multiplying the seconds with 0.3 would give you, in kilometres, how far it happened – an estimation of, course.

So, if there isn’t a mess of lightning strikes happening somewhere, which usually isn’t the case, and if you can clearly tell which sound came from which lightning strike, which you can’t in most cases, you can actually estimate the distance of a strike very easily.

If you think that’s great. You might be interested in:
How to estimate the temperature.
and How to estimate the time to sunset.

[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.

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…

First Man-made Object in Space – A Manhole Cover?

By Anupum Pant

Edit: The first man-made object to cross the boundary of space (100 km above the sea level, or the karman line) a Nazi German V2 rocket on October 3, 1942. – As mentioned by Scott and Adolf in the comments.

Background

Odd, I know. Teachers would say Sputnik was the first ever man-made object to orbit earth, but there is a slight possibility that Sputnik might not have been it – it could have been a humble manhole cover (not so humble, read on).

Back in the year 1956 (or summer of 1957, but definitely before the launch of Sputnik which happened on 4th October 1957), scientists at Los Alamos were learning to contain a nuclear explosion. To find out, they decided to do a much much larger version of the fire-cracker-in-a-can trick…
I’m not sure if they were doing it out of a desire to loft objects in space using a novel nuclear bomb propulsion, or it was something else, it sure was madness.

The mad experiment

In a 500 feet long and 4 feet wide vertical cylindrical tunnel, they put a nuclear bomb. The top of this tunnel was sealed using a 4 inch thick man hole cover (on steroids). The lid weighed about 2 tons! They were sure that even the 2 ton lid would blow off like feather due to the nuclear explosion. However, they weren’t sure on exactly how fast it’d travel up. To measure the speed, high-speed cameras were placed near the opening.

The bomb was detonated. Some say that the high speed cameras were only able to capture the image of the lid in a single frame. Which by the way could also contribute to an enormous error margin in the speed calculation. Nevertheless, the speed was of the lid at which it flew up in the air was calculated to be 41 miles per second – approximately 6 times the escape velocity! Never before had any man made objects moved at that speed inside the earth’s atmosphere. The lid went. It was never seen again. No one knows where it is now.

It’s highly likely that the lid was burned up and never reached Space. Or, may be it did reach some place and then dropped back. Again, must have got burnt during re-entry. Nothing can be said for sure.

Another thing that could have happened is that the lid went on and started orbiting the earth – highly unlikely, still. It’s probably still floating up there. And if things weren’t worse already, think of this – the first man-made object ever to orbit the earth was a manhole cover? Or, the fastest man-made object ever to travel inside the earth’s atmosphere was a manhole lid? Damn!

[Source 1] [Source 2]

Outperforming Humans – Speed

By Anupum Pant

Humans can use tools, communicate, count, make others laugh, socialize and are self aware too. We also have emotions and a pretty good memory. All of the things put into a single creature sure makes the “most advanced” creature we’ve ever known. But if these traits are considered individually, you’ll easily find an animal who beats us at one trait at a time. Today, I wanted to read and write about where humans stand when it comes to speed.

Talk about running speeds and the fastest person ever, Usain Bolt comes to my mind. A bolt indeed. As on date, if I’m not wrong, the world record set by him in the 100m race is 9.58 seconds. To put this human freak show into perspective, the average speed of the Jamaican sprinter in this race comes to about 37 km per hour (23 miles per hour).  And he’s clocked 28 mph somewhere in the race, they say.

In a world full of cars and planes, where distances travelled have become really huge, 28 mph sounds like a speed which does no good in our practical lives. And yet, it takes an Olympic runner to clock that speed. Normally, people run at about, say 10 mph. Damn!
The biological human limit to running speeds is estimated to be about 40 mph.

Quick fact: The fastest human objects ever are Helios 2 (a German probe) clocks about 150,000 mph. Another spacecraft, Juno does about 25 miles in a single second!

Now compare that with a Peregrine Falcon which can make use of the gravity and its perfectly aerodynamic body to travel at a speed of 216 mph (360 kph). But, that’s hardly any work for the animal. It’d the gravity making it fall.

In level flight, the white throated needletail (swift) can fly at speeds more than 100 miles per hour (up to 106). That’s the fastest bird if you do not count gravity assist.

An on land, of course the Cheetah takes the prize with about 70 mph of running speed. But, there’s a catch. If you measure speeds of animals relative to their body sizes, there’s a little blood sucking mite that beats cheetah by a huge margin.

The fastest swimming fish is the sailfish, which can swim and jump for small distances at about 70 mph.

Humans can swim at about 5 miles per hour.

Moving at 35 miles per hour a jack rabbit can travel faster than a human. The patas monkey, the fastest primate, runs at about 35 miles per hour too!

Now these are some animals you probably already know. Soon there’s more to come. In the coming days I wish to do a series on outperforming humans…Maybe I’ll write about endurance next.

Keep reading for more.

Is Cheetah No Longer the Fastest Land Animal?

By Anupum Pant

Read this for the answer to the question above

If you haven’t previously heard of the Betteridge’s law of headlines, also known as the Davis’ law or the journalistic principle, here’s what it says:

Any headline which ends in a question mark can be answered by the word no.

(Of course, you aren’t supposed to take the “law” too seriously.)

Did you see the headline for this article? So, basically you can read no further and still say – No, Cheetah still is the fastest land animal. But if you look deeper, things sure get interesting.

Absolute Speed vs. Relative Speed

To be specific, Cheetah is the fastest land animal because its absolute speed on land is the highest (112 to 120 Km per hour). When you measure absolute speed, you don’t take into account anything other than the speed. The weight or size of the animal doesn’t matter. Here, Cheetah is a clear winner.

But, when you do take into account the body length of an animal and measure the speed in terms of, number of body lengths the animal can cover in a single second, there are number of other animals that beat Cheetah by a huge margin.

Here’s a fact – When running at full speed, cheetahs can cover the length of up to 16 to 20 cheetahs in a single second. That’s pretty fast. The fastest humans on earth can do about 10 – 11 body lengths per second. [Source] Do you know what’s the fastest animal of you measure speed relative to their respective body lengths? Wait for it…

It is a mite. Yes, a tiny little 1-2 mm Californian blood sucker can cover up to 322 body lengths in a single second! Scientists just found out about it. Graphic designers who’ve used elegant cheetah silhouettes to represent speed in their graphics will have to use a tiny blood sucker now? How disappointing!

By the way, 322 body lengths in a single second of a sesame sized animal translates to just about 0.8 km per hour of absolute speed. But, imagine this. If it (the Californian mite) were the size of a human being (which it is not), it would have moved at a whopping 2,100 km per hour. I know the physics of it would have been different in case it were that big. Since it is not, we aren’t even putting in the effort to consider those details at the moment.

In case someone comes searching for the scientific name of this mite, it is called – Paratarsotomus macropalpis (I won’t remember that)

Other land animals “faster” than the Cheetah

  • The Australian tiger beetle held the record before they found out about the tiny mite. The beetle can cover up to 171 body lengths in a single second.
  • The household cockroach is pretty fast too. It does about 50 body lengths in a single second.
  • The ghost crab can run at about 100 body lengths per second.

All of them, much “faster” than the cheetah (in relative speed). And still Cheetah always wins the race because it is absolutely the fastest land animal. Still. Please don’t trust the click bait titles like:

Cheetah beaten to title of fastest animal in the world by tiny Californian mite

Moving Light Captured on Camera

By Anupum Pant

The speed of light

In vacuüm, light travels 299,792,458 meters in a single second. In other words, in a single second it travels 186,000 miles. To establish a  perspective, if I could move that fast, I would circumnavigate the world in 0.13 seconds. A hypothetical jet plane would take more than 2 days to do the same. In short, it is fast. It is the fastest – Nothing beats light.

If you try to record moving light on a home camera, you’d fail miserably. That is because normally they can roll only about 30 to 60 frames per second. In fact, you’d not even be able to capture a fast-moving ball without motion blur, forget recording moving light. To record fast things you need fast cameras that can roll several thousands of frames every second.

In the past, high-speed-cameras, rolling film at thousands of frames per second have been able to record bullets moving in slow motion, bubbles bursting, people getting punched and what not! MythBusters use such cameras for almost every experiment they do.

But light travels a million times faster than bullets. Till the year 2011, to capture moving light on film was considered an impossible feat; and then, a team from MIT media lab invented this.

A 1,000,000,000,000 FPS camera

A camera that can record at a speed equivalent to a theoretical one-trillion-FPS camera was invented by a team at MIT media labs in the year 2011. This camera can record light moving through space, in slow motion! To look at what it can do, you’ll have to watch the video below. In the video, the researcher explains its mechanism in detail.

It is theoretically impossible to craft a mechanical device that can roll film at such extremely high speeds. To tackle this physical limit, these geniuses invented a whole setup containing several cameras sensors that work together to make this feat possible.

Note: In reality, the camera doesn’t record the footage of a trillionth of a second. It is a composite video of lines of different pulses of a laser recorded and stitched together. The time it takes to compile enough data for the video, is more than what it takes the light to travel from one end to another.

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Prince Rupert’s Drop – Exploding Glass

By Anupum Pant

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What is it?

At first, a Prince Rupert’s Drop is an interesting yet harmless looking drop of glass with a long tail. It looks like a tadpole: [image]

It is no different from an annoyed person who refuses to let out his resentment – A slightest something might make him explode suddenly, but it isn’t easy to make him let it out. Confused? Read on…

Now, think of a glass drop that has immense amounts of potential energy stored inside it – It explodes (actually implodes) when the tail is disturbed, but it is impossible to hit it hard with a hammer and break it.

How?

A Prince Rupert’s Drop is formed when a drop of molten glass is suddenly dropped into a water bath. This quick cooling, solidifies the surface fast, while the inner part remains molten. Now, glass formed on the surface, being a poor conductor of heat doesn’t allow the inner part to cool quickly. When the inner part starts cooling, it tries to shrink and pulls the surface towards it. As a result, great amount of potential energy gets stored inside, in the form of stresses (stresses are seen using a polarized filter). This stored energy gets released when the tail is disturbed – It explodes into very tiny pieces of glass.

Toughened glass – a stronger variety of glass used in several places – also uses a similar technique to make strengthened glass.

On Wikipedia, a user asked about the possibility of utilizing the energy released from this explosion, being used to fire a bullet from a barrel. An interesting possibility, I must say.

The Name

Prince Rupert of Rhine did not discover the drops, but played a role in bringing them to Britain. He gave them to King Charles II, who in turn delivered them to the Royal Society for scientific study. Prince Rupert’s Drop was a widely known phenomenon among the educated during the 17th century – far more than now.

Watch it being explained better

Probably the best demonstration of this glass drop exploding is right here on the internet. Couple of months back, a YouTuber, Destin (Channel: SmarterEveryDay) posted a video demonstrating the physics behind it. He recorded  the progression of the explosive fracture using a hi-speed camera (at more than 100,000 frames per second) and calculated the speed of the fracture travelling through its tail (~ 1.5 miles per second). I’ve attached it below for you to watch.