Shadowing Practice: Is spider web really stronger than steel? - Learn English Speaking with Video
Les maken...
1
- This is the largest amount of spider silk that's ever been put together for a test like this.
2
So I'm gonna put it to the ultimate test, and try to be the first person ever to swing from spider silk.
3
I don't know if it's going to hold my weight, so let's see.
4
In three, two, one. - In "Spider-Man Two," Peter Parker is on a runaway train full of passengers.
5
And to stop it from derailing, he stands in front of the train, fires webs at the buildings around him, and holds on.
6
The webs stretch, some of them snap, but they do just enough to slow down the train and save everyone on board.
7
It sounds like something straight out of a comic book.
8
But real spider silk, the fiber that makes up a spider's web, well, it truly might be this incredible.
9
It's reportedly stronger than steel. It's pretty strong.
10
That's crazy!
11
And 10 times tougher than Kevlar.
12
To find out if that's really true, I went to the Blackledge Spider Lab at the University of Akron, one of the world's leading research centers studying spider silk.
13
Before I went to the lab, I'd always assume that a spiderweb was made from just one kind of silk.
14
But that's actually not the case.
15
One type of silk anchors the web to a surface.
16
Another forms this stretchy spiral, and a different sticky silk catches prey.
17
Once something's trapped, the spider switches to yet another silk to wrap it up.
18
- The threads are all thinner than your hair, so they're going to look pretty similar to each other unless you use a microscope.
19
- All in all, there are seven different types of silk, but the strongest is the dragline silk, which holds the web in its place.
20
- We've got the two main structural threads in this web.
21
So the spokes on the wagon wheel and the outer framework here, that's all the dragline silk.
22
It's called major ampullate silk if you want the fancy word.
23
- The major ampullate is that one that commonly compared to steel?
24
- Yes! - Okay.
25
- Absolutely.
26
And that's partly because it's function in a web like this.
27
A bug hits it, to stop that moving bug, most of the work is done by the dragline silk.
28
- To do this, the dragline silk has to be incredibly strong.
29
So to find out how it compares to steel, we wanted to run a test, but it turns out that getting the sample isn't so easy.
30
All right, we've taken a garden variety spider and knocked it unconscious using CO2.
31
We brought it over here and we put it down with tape.
32
I then started pulling out the dragline silk by hand.
33
It's so light that you can barely feel it.
34
We've attached it to this big rotating mechanism which they custom made to milk spiders.
35
No spiders were harmed in the making of this video.
36
Now that we've got our silk, we can put one strand into a machine that slowly pulls on our sample.
37
And as it pulls, we'll monitor two key properties.
38
When you pull on the silk, that force is spread over a tiny cross-sectional area.
39
If you divide the force by that area, you get the stress.
40
Now, as you pull, the silk is also stretching.
41
To see just how much, we divide the change in length by the original length to get a measure called the strain.
42
At first, as the stress increases, the strain increases roughly in proportion.
43
And if we stop pulling here, the silk would spring back to its original length.
44
But keep pulling and eventually it passes a point where some of that stretching becomes permanent.
45
And it's pulling.
46
- All right.
47
You film that, I'm going to be filming this.
48
- And it broke. - Wow!
49
- Eventually, if you keep pulling on the silk, it will break.
50
And at that point, the force applied, divided by the cross-sectional area is called its ultimate tensile strength.
51
- We're at about 600 megapascals.
52
- To put that in perspective, if you had a rope of spider silk that had a cross-sectional area of one square centimeter, roughly the size of your little finger, it could support about 60,000 newtons of force.
53
That's the weight of a fully grown African elephant.
54
And that's not even the strongest spider silk out there.
55
- Breaking stress wasn't incredible for this piece of silk.
56
- Deep in the jungles of Madagascar lives the Darwin's bark spider.
57
Its diet consists of flying insects that zip over wide rivers.
58
So to catch its prey, the Darwin's bark spider has to spin giant webs that stretch up to 25 meters over open water.
59
And to survive that kind of distance and tension, its silk has to be incredibly strong.
60
It has an ultimate tensile strength of around 1,600 megapascals.
61
That's more than twice the strength of our sample.
62
But experimental ultra high strength steels can reach an ultimate tensile strength of nearly 3,000 megapascals.
63
That's about three times that of typical dragline silk, but steel is also about six times denser.
64
So for two ropes with the same mass and length, the silk rope has six times the cross-sectional area.
65
Six times the area at one third the strength, well, that gives a rope that can take twice the force before it snaps.
66
This measure of strength relative to mass is called specific strength.
67
And it means that for the same mass and length, spiderwebs can withstand roughly twice the force of ultra high strength steel before breaking.
68
- So that's where ounce for ounce, spider silk is quite strong.
69
You got to think about what is the application you're talking about using this material in.
70
Is it somewhere where you don't care about weight, and you need the strength?
71
Then steel's going to be perfectly fine.
72
But if weight matters, spider silk is really the champion there for tensile strength.
73
- But strength alone isn't enough.
74
To see why, look at rock climbers.
75
If a rock climber was just hanging, all we would care about was if the rope could support their weight.
76
That's strength. But climbers don't just hang, they fall.
77
And now the rope has to bring them to a stop, which means absorbing that kinetic energy.
78
Stop the fall in a short distance, and the energy has to be absorbed quickly.
79
The forces are enormous.
80
Stretch it out and that same energy is absorbed gradually, so the forces are lower.
81
So to absorb more energy without snapping, it has to stretch further.
82
And that's actually not so different from spider silk.
83
- So a bug hits this web, you've got to stop the flight of that bug pretty quickly.
84
And you could do it by just building a really stiff structure.
85
Think like a brick wall, you throw a tennis ball against it.
86
You're gonna stop that ball instantly.
87
But that doesn't work very well if you want to catch a meal.
88
- It'll bounce off. - Because it'll just fall out.
89
And so it helps to slowly decelerate the insect so that the web has time to stick to it, and keep the meal for the spider to subdue.
90
- So the spider silk has to be quite stretchy.
91
- This piece of silk stretched to 70% of its length before it broke, which is really exceptional for dragline silk.
92
- Now, every tiny bit of stretching absorbs a little bit of energy.
93
If you add all these tiny amounts together, the result is the total energy the material absorbs before breaking.
94
On a stress/strain graph, it's proportional to the area under the curve.
95
This is the material's toughness.
96
Kevlar, the material used in bulletproof vests, whose whole job is to take the energy of a bullet and spread it out before it reaches the body, well, it has a toughness of up to 50 megajoules per cubic meter.
97
Experimental ultra-high strength steel has a toughness of around 170 megajoules per cubic meter.
98
But spider silk?
99
- This piece of silk had a toughness of about 205 megajoules per cubic meter.
100
- Oh, okay. So that might be like four times Kevlar.
101
But the silk from the Darwin's bark spider can have a peak toughness of 520 megajoules per cubic meter.
102
That's roughly three times the strongest steel out there, and 10 times as tough as Kevlar.
103
See, Kevlar has a very high tensile strength, but it's also quite stiff.
104
Compared with stretchy spider silk, that means that the stress/strain graph rises sharply and fails before it can stretch very far.
105
So it's not able to absorb as much energy.
106
And that's why spider silk wins on toughness.
107
- But it's the ultimate in green chemistry.
108
They're not using the high temperature, or the caustic solvents that most of the polymer industry uses to make high performance threads.
109
They're doing it at room temperature, inside a living body, with the same basic building blocks that you use to build your hair and your skin.
110
- Now, the secret to spider silk's unbelievable natural strength lies in how those building blocks are arranged.
111
If you look inside a silk fiber, you'll find spider silk proteins called spidroins.
112
In some regions, the spidroins are arranged in similar size and shape, and they're closely aligned along its length.
113
They're kind of like stacked egg trays.
114
These are nanocrystals.
115
In other areas, the spidroins aren't so uniform.
116
Here they're less ordered, and they can move and change shape more freely.
117
These are called the amorphous regions.
118
Together, they work like a network of tiny rigid blocks connected by elastic cords, which I have in front of me.
119
When I pull on the network, the cords stretch, and they absorb energy.
120
The blocks don't stretch much, but each one connects to several cords, which spreads the pull across the network.
121
So the amorphous regions let the silk stretch while the nanocrystals help it withstand a much larger pull.
122
Together, they allow the silk to absorb a tremendous amount of energy before breaking, which makes it so tough.
123
The result is a material that's stronger than steel by weight and also tougher than Kevlar.
124
It sounds perfect for making climbing ropes, parachute cords, airbags, even bulletproof vests.
125
But we actually aren't using spider silk for any of that, even though we've been trying to for centuries.
126
In 1709, a Frenchman named Francois Xavier Bon painstakingly collected hundreds of spider egg sacs, boiled them, combed them like wool, spun them into thread, and then used them to make stockings that attracted the attention at the royal court.
127
But this was harder than it sounds.
128
As he later said, "The only difficulty now lies in procuring a sufficient quantity of spider bags to make any considerable work of it." Three centuries later, Simon Peers and Nicholas Godley led a years long project in Madagascar, in which teams of Malagasy workers gathered more than a million golden orb weaver spiders in the jungle by hand.
129
They extracted their silk and painstakingly wove and embroidered it into a single golden cape.
130
Why hadn't they tried farming the spiders instead?
131
Well, attempts to do that all run into the same problem.
132
Spiders are cannibals.
133
The big problem with spiders is that they eat each other?
134
- That's one of the big problems.
135
And then you can't just keep them in a tiny little container.
136
You're going to have to have a lot of real estate if you're going to have a farm with 10,000 spiders on it.
137
- Even if you could get your hands on that many spiders, as we've seen, milking them is difficult, and the spiders don't always cooperate.
138
- Really cooperative spider will give you 300 yards of silk.
139
100's a lot more typical, but they kind of have their own individual personalities.
140
Some of them will just break the thread right away, and not even cooperate with you.
141
- That's why natural spider silk is so scarce.
142
One supplier charges $700 for 100 milligrams, which works out to roughly $7 million per kilogram.
143
That's roughly 50 times the price of gold.
144
Okay, so we can't farm spiders for their silk, but we know what the proteins are, so surely we can just make them?
145
Well, scientists have tried.
146
By the late 1990s, researchers at DuPont took the genes that code for spider silk proteins and put them into E. coli and yeast.
147
These living cells are like protein factories.
148
One engineered cell quickly becomes millions.
149
It worked, but scientists wanted an even more efficient method.
150
So in 2001, a team in Germany tried implanting spider silk genes into plants like tobacco and potatoes.
151
But if you really want to produce a lot of protein in a concentrated form, look at milk.
152
To feed their young, mothers produce milk with high concentrations of proteins.
153
So around the same time, a Canadian company called Nexia tried something much stranger.
154
They put spider silk genes into goats, creating genetically modified spider goats.
155
No, no, really, they made spider goats.
156
These goats produce milk chock-full of spider silk proteins.
157
In one sense, it worked.
158
All the experiments were able to produce spider silk proteins, but they ran into the same problem.
159
From E. coli or yeast, these proteins were purified as a fine white powder.
160
From plants, the purified proteins formed a viscous, gelatin-like liquid.
161
And from goats, it was dissolved in the milk.
162
None of these even vaguely resemble spider silk.
163
- And that's one of the secrets that any company that really wants to mimic spider silk at an industrial scale needs to kind of figure out is how to process silk proteins the way spiders do.
164
- But that's easier said than done.
165
In a spider, it all starts in the silk gland in a region called tail.
166
Cells here make proteins called spidroins, and they secrete them into the fluid inside the gland.
167
Every spidroin has three main parts.
168
One end is called the N-terminal, and the other the C-terminal.
169
And between them is a long repeating sequence of amino acids.
170
This is called the repetitive region.
171
Once inside the tail, the C-terminal ends pair up, which links neighboring spidroins together.
172
But the N-terminal ends stay mostly separate.
173
So the spidroins are still loose enough to bend, coil, and move around.
174
Next, they move into the storage sac, where they're packed together at high concentrations.
175
Normally, proteins this concentrated would stick to each other, and clump into a solid, but this can be modified with a careful balance of salts and by changing the pH.
176
The pH is a measure of the concentration of hydronium ions in a solution.
177
And because hydrogen ions are little positive charges, you can think of the pH like a dial that controls the electrical charge on different parts of the protein.
178
In the storage sac, the pH is tuned so that the N-terminal ends carry a net negative charge.
179
Every protein carries the same charge.
180
And since like charges repel, when you crowd them together, they shove apart instead of sticking together.
181
Now, the spidroins are still crowded in this aqueous solution, and at such high concentrations, they begin to gradually rearrange.
182
The N-terminals are attracted to water.
183
These are hydrophilic.
184
While the repetitive region is repelled by it, this is hydrophobic.
185
So the spidroins rearrange, and you end up having these hydrophilic parts facing outward towards the water.
186
And hydrophobic parts tuck themselves inside away from it.
187
They then form these tiny structures called micelles.
188
And the micelles cluster together into larger globules.
189
These globules next enter the spinning duct.
190
- For the dragline silk, the duct is kind of S-shaped, but it gets skinnier and skinnier.
191
- As the globules go through the narrow duct, the liquid near the walls rubs against the surface, and it moves more slowly, while the liquid in the middle moves faster.
192
So the layers slide past each other, which is known as shear.
193
These shear forces stretch and deform the globule.
194
- You also remove some water, so water goes out.
195
You get a drop in pH, so it becomes a little bit more acidic as you go down this duct.
196
- So the proteins are then being changed in two ways at once.
197
Mechanically, they're being pulled and aligned.
198
And chemically, that drop in pH means that there are now more positive hydronium ions in the solution.
199
These bind to the negative parts of the proteins, neutralizing them.
200
Now all the proteins don't repel each other as strongly, and so the N-terminal ends begin pairing, linking the proteins into long chains.
201
These chains are pulled through a tiny narrowing called the drawdown taper, which leads to the spigot.
202
Here, the spider pulls the liquid through a small opening.
203
This forces the liquid to speed up.
204
And as it speeds up, it stretches.
205
It's this final stretch that pulls neighboring spidroins tightly alongside one another.
206
Now, depending on the sequence of amino acids, some sections fold into zigzag strands.
207
These strands then interlock and rows of hydrogen bonds stitch them into rigid, sheet-like structures, which stack together into the nanocrystals that give the spider silk its strength.
208
In other sections, the spidroins don't fold as neatly.
209
That's how you get the amorphous regions which give the silk its stretch.
210
Exactly how the proteins assemble inside the spinning duct is still being studied.
211
No one fully understands it yet, and that makes recreating the process in a lab quite difficult.
212
So scientists wondered, "What if instead of starting from scratch, you used an animal that already has a spinner?" This is exactly what researchers at Kraig BioCraft Laboratories, a biotech company in Michigan, have been working on.
213
What's more, they're doing it with an insect that humans have been farming for nearly 5,000 years.
214
According to legend, a Chinese empress was relaxing in her garden, when something fell into her teacup.
215
She looked inside, and saw a cocoon.
216
The hot water loosened it.
217
And when she lifted it out, it unraveled into a single shimmering thread.
218
So long that it stretched across her entire garden.
219
This was silk.
220
Whether or not that story's true, people eventually learned to farm the insect that made the thread.
221
Silkworms.
222
They're the caterpillars of the domesticated silk moth.
223
Silk quickly became one of the most valuable materials in the land.
224
It dressed emperors and spurred trade connecting East Asia and Europe.
225
So much so that it gave the trade route its name, the Silk Road.
226
For nearly 2,000 years, China guarded the secret.
227
But of course, people were always trying to steal it.
228
By the mid-sixth century, the Byzantine Empire was in trouble.
229
Plague had devastated the population.
230
And on top of that, the purchase of silk was draining its gold.
231
The problem was that Byzantines couldn't make silk.
232
Most of it had to come through Persia, the very empire it was fighting.
233
So Emperor Justinian made a secret deal with two monks.
234
They would travel east, find the source of silk, and then smuggle it back.
235
They returned with a secret hidden inside their hollow canes.
236
Silkworm eggs.
237
This may be the first recorded case of industrial espionage in history.
238
With that, Byzantium could finally make its own silk.
239
Nowadays, we farm them by the millions.
240
- One moth lays 500 eggs. - Okay.
241
- So when you talk about growing productions, right?
242
Like my wife and I had a baby.
243
These guys, they have 500 babies.
244
And they do it every 30 days.
245
- So the researchers at Kraig wondered, "What if we could make the silkworm spin spider silk instead?" - When we create a transgenic silkworm, we're taking the genetics of a silkworm, and the genetics of a spider, and we're putting those together.
246
We're taking the best aspects of both.
247
And that's what we're doing to create our fibers.
248
- They start by gluing eggs onto a slide, which they line up under a microscope.
249
- So this is the microinjection station.
250
We're talking about eggs that are the size of the head of a pen.
251
We're talking about needles that are half a micron in diameter.
252
- This part is the, I want to inject.
253
So as you see, this is the tungsten needle and this is the glass capillary.
254
And first we poke a hole with the tungsten needle.
255
I will actually move the eggs to the capillary and poke.
256
- The fluid carrying the spider DNA is then injected into the part of the egg that will eventually become the silkworm.
257
But at this point, the genes are still separate.
258
They have to become part of the silkworm's own DNA.
259
And luckily, nature already has a way of doing that.
260
If you take an insect like a moth and look inside its genome, you'll see some stretches of DNA that move around.
261
They jump from one place in the genome to another.
262
These are called jumping genes, or transposons.
263
One specific one is called piggyBac, and it was first identified in a cabbage looper moth.
264
PiggyBac is a piece of DNA with two short sequences at its ends, and it works together with an enzyme that recognizes these ends, cuts the whole piece out, and inserts it somewhere else in the genome, kind of like a natural cut and paste system.
265
What scientists realized is that if the enzyme only looks at the two ends, then you can keep those ends the same, but change what sits in the middle, and use that to implant the DNA of your choosing.
266
So in the lab, the DNA in the middle is replaced with the spider silk gene.
267
This, together with separate instructions for making the enzyme, is what's then injected into the silkworm egg.
268
And inside the egg, the enzyme recognizes the familiar end sequences and cuts and inserts the spider silk gene into the silkworm's DNA.
269
If everything works, it becomes a permanent part of the silkworm's genome.
270
Now with silkworm where the edit worked looks almost exactly like one where it didn't.
271
- The first approach we used was creating transgenics with the glowing cocoon.
272
A green fluorescent protein is what's making these guys glow that green color under this particular wavelength with that particular light filter in front of it.
273
- It feels magical.
274
And there's a living thing inside of it.
275
- Mm hmm, yep.
276
- And it's creating the glowing effect.
277
- Yeah.
278
- But even if the DNA insertion is successful, it might not have ended up in the right place.
279
- If I create the world's best recipe for chocolate chip cookies, and I stick it in the pasta section- - Yeah.
280
- You're probably not going to make a lot of chocolate chip cookies, right?
281
'Cause you're not going to see it.
282
- Yeah. - Same thing for this, right?
283
We want the recipe in the right section of the right cookbook.
284
- That's why getting the spider silk gene into the silkworm isn't enough.
285
- We really want the spider silk get incorporated into their silk gland, not any other tissue.
286
- But piggyBac only looks for a four-letter DNA sequence.
287
TTAA. - There's so many TTAA in their genome.
288
You couldn't really control where they were.
289
- So it's like there are a lot of different places where they could park. - Yeah, yeah, that's true!
290
- And that means that it won't spin pure spider silk.
291
If you had to estimate, of the transgenic silk, like what percentage is spider DNA?
292
- Like 6%, 10%. - That's insane to me!
293
So even with this limited gene transfer, the fibers still achieve much of the mechanical performance of pure spider silk.
294
- Our average samples are usually about 60% of spider silk, right?
295
Which, show me any other place in the world where you can get materials that perform at 60% the strength of spider silk that you can make cost effectively, right?
296
- To push the 60% average even higher, the insertion needs to be more targeted.
297
- The next step is to create pure, what are called knock-in/knockout transgenics where we will completely remove all aspects of the silkworm's native DNA for the silk, and replace that completely with the spider silk protein.
298
- And to do that, most of the leading labs in the field are exploring CRISPR-Cas9.
299
This tool has two parts.
300
The first is a guide, a short piece of genetic code designed to match one exact stretch of DNA.
301
Unlike piggyBac, which recognizes a sequence just four DNA letters long, this guide matches about 20 letters, making it far more specific.
302
The second is a cutting protein.
303
When the guide finds its matching sequence, the protein cuts the DNA.
304
Here, that spot is inside the silkworm's own gene for making silk.
305
The cell immediately tries to repair the break, and scientists take advantage of this by also injecting donor DNA, carrying the spider silk gene.
306
As the cell repairs the cut, it copies in that donor DNA, stitching the spider silk gene into this one precise location.
307
But this process is still an active development.
308
And Kraig is not the only group chasing the dream of spider silk.
309
In Germany, AMSilk is making proteins for fibers, coatings, powders, and hydrogels.
310
And in Japan, Spiber is brewing protein fibers through fermentation.
311
Brands like Goldwin and The North Face have already used a version of these fibers in their clothing.
312
And the military has been interested too.
313
In 2016, the US Army funded Kraig to produce ballistic shoe packs, panels layered with transgenic silk that are designed as potential body armor.
314
And it's even being explored in medicine.
315
For centuries, surgeons have stitched wounds together with silk.
316
But now a company called Newrotex is using spider silk to help repair damaged nerves.
317
So if it can be produced cheaply, spider silk could find its way into clothing, armor, implants, even nerve repair.
318
But to do that, we're going to need a lot of it.
319
- And this is our specialized spider silk. There you go.
320
- This is the transgenic spider silk.
321
- This is spider silk.
322
This is transgenic spider silk.
323
- What? This is like a bale.
324
This is a hay bale of spider silk.
325
- So last year we produced about a half a ton of spider silk cocoon. - Half a ton.
326
- And this is silk from that.
327
- But what about our original question?
328
Can you use transgenic spider silk to swing like Spider-Man?
329
So Derek, I've got you here in a climbing gym for a very good reason.
330
And the reason is underneath this dirty dish towel.
331
- Unveil it, unveil it. Yeah, go.
332
All right, okay. This looks very uninspiring.
333
- So what's interesting is this is one continuous filament.
334
- This is just one strand.
335
- But each one of these strands is actually 10 individual silk filaments that are kind of connected. - All right.
336
So you want me to hang from this?
337
- I do want you to hang from it, yes.
338
I actually want you to do more than just hang from it.
339
I want you to swing.
340
- This will be the first time ever anyone has ever swung from actual spider silk.
341
Granted this spider silk came from other organisms, but...
342
I don't know if it's going to hold my weight, so let's see.
343
In three, two, one.
344
- You really came close! - Don't tell anyone, but Spider-Man.
345
- Okay, so we've seen it can hold your weight pretty reasonably.
346
We could swing, but I do want to put it to the ultimate test and get you up there.
347
How much do you trust spider silk?
348
- Tensile strength doesn't lie.
349
- All right, let's get you up there.
350
- We used the title, "Risking my life to settle a physics debate" too early.
351
It feels like it's going to dig into my fingers.
352
- This is crazy. - I'm going to go. I'm going to go!
353
- Whoo! Let's go!
354
- You got to see my finger, man!
355
- Ooh, damn!
356
- Yeah. This is the problem with spider silk.
357
Just, it's thin, it's strong, and it just rips you open.
358
- Now, if it isn't clear, we're not exactly web-swinging experts.
359
But we'd love to get the silk into of the hands of someone who is.
360
- Tom Holland, this is a challenge.
361
Yeah, I'm calling out Tom Holland.
362
I'm calling out all them guys.
363
Andrew Garfield, Tobey McGuire.
364
That's right. Come at me, bro.
365
- See, spider silk is so strong and so thin that it actually cut Derek's skin.
366
And that's actually a great way to explain the design flaw with modern razors.
367
Thanks to Henson Shaving for sponsoring this video.
368
See, facial hair resists more than you think.
369
And many razor blades are engineered so thin that they bend under that resistance.
370
This is called blade flex.
371
Now, most razors actually build this flex in.
372
They use springs, pivots, and flexible mounts that allow the blade to move.
373
It's supposed to make the shave feel gentler, but it means that the cutting angle is constantly changing.
374
When unsupported, the blade bends mid-stroke and instead of slicing cleanly, it tugs the hairs, micro-cutting the skin.
375
That's what causes irritation.
376
The usual fixes are lubrication strips or extra blades, but they don't solve the real problem.
377
The blade is still allowed to flex.
378
We assume that razor bumps and irritation are inevitable, but that's shaped by bad design.
379
But Henson is designed by aerospace machinists who control cutting forces with high precision.
380
And their razors use a single precisely-machined blade.
381
Instead of letting it move, Henson's design supports the cutting edge with tight machining tolerances, holding the blade securely so the angle is consistent.
382
Remove the flex, remove the irritation.
383
Use code "Veritasium" for 100 free blades with any razor purchase.
384
Just add both the razor and blades to your cart.
385
Thanks to Henson Shaving, and as always, thanks for watching.
📺 Zelfde Kanaal
C11
Something is jamming GPS over Europe. Here's what we found
IELTS PrepTOEFL PrepUniversity Students
C11
Why It Was Almost Impossible to Make the Blue LED
Business EnglishUniversity StudentsWorking Adults
C12
You've (Likely) Been Playing The Game Of Life Wrong
Business EnglishUniversity StudentsWorking Adults
B22
We're trying something new...
C120
How does light 'know' the shortest path?
IELTS PrepTOEFL PrepUniversity Students
C12
The CIA's new tech doesn't make sense
IELTS PrepTOEFL PrepUniversity Students
C11
Why does every mammal get 1 billion heartbeats in their life?
IELTS PrepTOEFL PrepUniversity Students
C13
Why Cold Drinks Were Deadly Before 1914
Business EnglishUniversity StudentsWorking Adults
C14
Exposing The Flaw In Our Phone System
Business EnglishUniversity StudentsWorking Adults
C12
Our Greatest Delusion
IELTS PrepTOEFL PrepUniversity Students
C13
The Most Controversial Problem in Philosophy
IELTS PrepTOEFL PrepUniversity Students
B25
Why Boredom is Good For You
Daily ConversationUniversity StudentsWorking Adults
B24
Why Are 96,000,000 Black Balls on This Reservoir?
IELTS PrepTOEFL PrepUniversity Students
C13
We've Been Using The Wrong Science In Court For 50 years
IELTS PrepTOEFL PrepUniversity Students
B24
Explaining Pi With Pizza
University Students
B214
5 Fun Physics Phenomena
Daily ConversationUniversity Students
C11
The Most Misunderstood Concept in Physics
IELTS PrepTOEFL PrepUniversity Students
B11
Falling ladders - why does this happen?
IELTS PrepTOEFL PrepHigh School Students
C110
How a slinky falls in slow motion #shorts
University StudentsWorking Adults
C13
We're 99.9% sure this pattern is true, but no one can prove it
IELTS PrepTOEFL PrepUniversity Students
✨ Aanbevolen Video
C112
30 zinnen
How Realistic Is Spider-Man's Web Slinging Antics?
IELTS PrepTOEFL PrepUniversity Students
C1552 zinnen
The Professor Who Taught People How To Think (1962)
IELTS PrepTOEFL PrepUniversity Students
C115
43 zinnen
Candy Corn In Space
IELTS PrepTOEFL PrepUniversity Students
C13
133 zinnen
TOEFL Listening Practice | Lecture | Arachnophobia
TOEFL PrepUniversity StudentsWorking Adults
C12
77 zinnen
1,000km Cable to the Stars - The Skyhook
IELTS PrepTOEFL PrepUniversity Students
C14
135 zinnen
String Theory
IELTS PrepTOEFL PrepUniversity Students
B23
332 zinnen
How Vietnamese Tunnels Outsmarted the U.S. Military
IELTS PrepTOEFL PrepUniversity Students
C14
41 zinnen
The Building Blocks of Everything: Matter & its Properties
IELTS PrepTOEFL PrepUniversity Students
B25
207 zinnen
Why Do Deep Oceans Have So Many Giants?
IELTS PrepTOEFL PrepUniversity Students
C13
80 zinnen
FINALLY: A Proof that Particles Take All Paths At Once?
IELTS PrepTOEFL PrepUniversity Students
C12
249 zinnen
The Speed of Light Isn't a Limit. It's a Converter
IELTS PrepTOEFL PrepUniversity Students
Woordenschat en spreektips bij deze les
Deze video bevat 385 zinnen en 4945 woorden om na te spreken. Het gesproken deel duurt 26:49. De spreker praat snel, ongeveer 184 woorden per minuut, dus reken op verbonden en ingeslikte klanken. Slechts 75% van de woorden hoort bij de 3.000 meest gebruikte Engelse woorden, dus de woordenschat is pittig.
Belangrijke woorden in deze video
15 woorden uit de video die het leren waard zijn, met uitspraak en betekenis:
| Woord | Uitspraak | Betekenis |
|---|---|---|
| silk zelfstandig naamwoord | /sɪlk/ | zijde, rag |
| spider zelfstandig naamwoord | /ˈspaɪ̯dɚ/ | spin, kobbe |
| stretch werkwoord | /stɹɛt͡ʃ/ | strekken |
| gene zelfstandig naamwoord | /d͡ʒiːn/ | gen |
| blade zelfstandig naamwoord | /bleɪd/ | blad, lemmet |
| thread zelfstandig naamwoord | /ˈθɹɛd/ | draad, garen |
| sequence zelfstandig naamwoord | /ˈsiː.kwəns/ | volgorde, reeks |
| rope zelfstandig naamwoord | /ɹoʊp/ | touw |
| roughly bijwoord | /ˈɹʌf.li/ | grofweg |
| absorb werkwoord | /æbˈsɔɹb/ | absorberen, (in zich) opnemen |
| liquid zelfstandig naamwoord | /ˈlɪk.wɪd/ | vloeistof |
| spin werkwoord | /spɪn/ | draaien |
| goat zelfstandig naamwoord | /ɡoʊt/ | geit, bok |
| genome zelfstandig naamwoord | /ˈd͡ʒiː.noʊm/ | genoom |
| duct zelfstandig naamwoord | /dʌkt/ | buis, leiding |
Phrasal verbs die je zult horen
| Woord | Betekenis |
|---|---|
| find out werkwoord | ontdekken, onderzoeken |
| end up werkwoord | belanden, terechtkomen |
| fall out werkwoord | in onmin raken |
| figure out werkwoord | uitvogelen, er achter komen |
| go down werkwoord | afdalen |
| go out werkwoord | naar buiten gaan |
| slow down werkwoord | afremmen |
| turn out werkwoord | uitvallen, resulteren |
Grammatica in deze video
De structuren die de spreker het meest gebruikt, met de exacte woorden uit de video:
| Structuur | In de video |
|---|---|
| Present perfect continuous have/has been + -ing — iets dat eerder begon en nog bezig is | we've been trying · have been working · have been farming |
| Lijdende vorm be + voltooid deelwoord — het gaat om wat er gebeurt, niet om wie het doet | been put · was made · is done |
| Present perfect have/has + voltooid deelwoord — iets uit het verleden dat nu nog telt | we've taken · We've attached · we've seen |
| Betrekkelijke bijzinnen who / which + zin — extra informatie over een persoon of ding | stop, which means · broke, which is · breaking, which makes |
Uitspraak om op te letten
De spreker gebruikt 75 samentrekkingen en verkorte vormen, zoals don't, they're, we're. Spreek ze kort uit, zoals je ze hoort.
- De “th”-klanken: thread /ˈθɹɛd/, thin /ˈθɪn/, clothing /ˈkloʊðɪŋ/, withstand /wɪðˈstænd/, sixth /sɪksθ/
- De klanken “sh” en “zh”: concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, efficient /ɪˈfɪʃənt/, sheet /ʃit/, sufficient /səˈfɪʃənt/, tissue /ˈtɪʃ.(j)u/
- Lange woorden — let op de klemtoon: concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, incredibly /ɪŋˈkɹɛdɪbli/, experimental /ɪkspɛɹəˈmɛntəl/, cooperate /kəʊˈɒp.ə.ɹeɪt/, repetitive /ɹɪˈpɛtɪtɪv/
Zo oefen je met deze video
- Luister de hele video één keer zonder te spreken en noteer de woorden die je niet kent.
- Begin op 0,75× snelheid, spreek zin voor zin na en ga terug naar normale snelheid zodra het makkelijk gaat.
- Neem jezelf op en vergelijk met het origineel; let daarbij op woorden als silk, spider, stretch.
Wat is de Shadowing-techniek?
Shadowing is een wetenschappelijk onderbouwde taalleermethode die oorspronkelijk is ontwikkeld voor professionele tolkentraining en gepopulariseerd door polyglot Dr. Alexander Arguelles. De methode is eenvoudig maar krachtig: je luistert naar native Engelse audio en herhaalt het onmiddellijk hardop — als een schaduw die de spreker volgt met slechts 1–2 seconden vertraging. In tegenstelling tot passief luisteren of grammaticadrills, dwingt shadowing je hersenen en mondspieren om echte spraakpatronen tegelijkertijd te verwerken en te reproduceren. Onderzoek toont aan dat het de uitspraaknauwkeurigheid, intonatie, ritme, verbonden spraak, luisterbegrip en spreekvaardigheid aanzienlijk verbetert — waardoor het een van de meest effectieve methoden is voor IELTS Speaking-voorbereiding en echte Engelse communicatie.