Testing If You Can Blow Your Own Sail

Mark Rober
2 Mar 202417:06

Summary

TLDRThis engaging video explores a series of intriguing physics and engineering puzzles through hands-on demonstrations. From unraveling the mystery behind the moon's orientation in different hemispheres to investigating the Coriolis effect's role in draining sinks, each puzzle unveils fascinating scientific principles. The video also debunks common myths, such as sailboats propelled by sails and backpacks that reduce impact forces. With a blend of humor and scientific curiosity, the presenter aims to not only reveal the right answers but also foster a deeper understanding of the underlying theories.

Takeaways

  • ๐Ÿšจ The Coriolis effect, while influencing large weather patterns like hurricanes and cyclones, has a negligible impact on water drainage patterns in sinks and toilets due to its minimal effect on small scales.
  • ๐Ÿ’ก The moon appears upside down in the Southern Hemisphere compared to the Northern Hemisphere due to the Earth's spherical shape and the observer's perspective change from different hemispheres.
  • ๐Ÿ† An ellipse's unique property is that lines from one focus point will always reflect off the inner wall to the other focus point, demonstrated through both light reflections and sound waves.
  • ๐Ÿš— Newton's laws of motion explain everyday phenomena, such as why balloons move backward in a braking car due to the forward movement of denser air.
  • ๐Ÿšข Sailboats cannot be propelled by wind generated from a fan on the boat itself due to the principle of action and reaction, but external propulsion methods, like propellers, effectively utilize the surrounding medium.
  • ๐Ÿ’ฅ Adding just 6.28 feet of extra rope allows for a foot clearance all around the Earth, illustrating the concept of circumference increase relative to radius extension.
  • ๐Ÿ“– The HoverGlide backpack, designed to reduce impact forces by suspending the load, shows mixed practicality depending on the terrain and the synchronization with the wearer's movement.
  • ๐Ÿ“ˆ The demonstration of water swirling in different directions on either side of the equator for tourists is misleading, utilizing subtle pouring techniques rather than true scientific principles.
  • ๐Ÿ”ฎ Understanding the principles behind everyday physics and engineering puzzles enriches our curiosity and knowledge, as showcased through various demonstrations.
  • ๐ŸŽ‰ Engaging with hands-on experiments and projects, like those offered by CrunchLabs, can foster a passion for STEM and provide ah-ha moments of learning through fun and exploration.

Q & A

  • Why does the moon appear upside down in the Southern Hemisphere compared to the Northern Hemisphere?

    -The Earth is a sphere, so when viewed from the North Pole, the moon's orientation appears upright. However, when viewed from the South Pole, the moon appears upside down due to the difference in perspective.

  • How do ellipses work, and what are their special properties?

    -An ellipse is a geometric shape formed by connecting two focus points with a string. Any straight line shot from one focus point will bounce off the ellipse's interior wall and hit the other focus point. This property makes ellipses useful for acoustics, as sound can travel efficiently between the two foci.

  • Why do balloons move backward when brakes are applied in a car?

    -When brakes are applied, the heavier and denser air inside the car sloshes forward due to inertia, forcing the lighter helium balloons backward. This is because the air has more mass than the helium gas in the balloons.

  • Can a fan effectively power a sailboat?

    -No, blowing wind on a sail cannot effectively propel a sailboat. The fan would need to be placed underwater to push against the denser water and move the boat forward, similar to how a boat propeller works.

  • What is the Coriolis effect, and how does it relate to the direction of water draining?

    -The Coriolis effect causes weather patterns and ocean currents to spin in different directions in the Northern and Southern Hemispheres due to the Earth's rotation. However, this effect is too small to significantly impact the direction of water draining in sinks or toilets.

  • Is the tourist demonstration of water draining in opposite directions at the equator a scam?

    -Yes, the demonstration is a scam. The presenter subtly twists the water pour to make it appear like the water is swirling in opposite directions on either side of the equator, which is not actually the true equator.

  • How does the floating backpack claim to reduce impact forces?

    -The backpack is designed to suspend the load on an elastic track, allowing it to remain vertically stationary while the wearer moves up and down, potentially reducing the impact forces on the wearer's body.

  • Does the floating backpack effectively reduce impact forces in real-world hiking conditions?

    -According to the video's assessment, the backpack can be beneficial on flat, predictable terrain but is not worth the extra weight and potential issues on rough, sporadic hiking terrain.

  • What is the significance of the extra rope demonstration?

    -The demonstration shows that regardless of the size of the circle (e.g., the Earth or a basketball), the amount of extra rope needed to raise the entire loop one foot off the ground is always the same (approximately 6.28 feet), illustrating a mathematical principle.

  • What is the purpose of the CrunchLabs subscription service mentioned in the video?

    -CrunchLabs is a subscription service that sends fun toys and educational videos to subscribers each month, teaching them about physics, engineering principles, and how to think like an engineer through hands-on activities.

Outlines

00:00

๐ŸŒŽ Understanding the Moon's Orientation in Different Hemispheres

This paragraph discusses the reason behind the apparent upside-down orientation of the moon in the southern hemisphere compared to the northern hemisphere. It explains that since the Earth is a sphere and the moon orbits around it, the moon appears upright from the northern hemisphere's perspective, but upside-down from the southern hemisphere's perspective. The segment also demonstrates the sideways orientation of the moon at the equator, confirming the provided explanation.

05:04

๐Ÿ”ด The Physics of Ellipses and Their Acoustic Properties

This paragraph introduces the concept of ellipses and their unique focus points. It explains that any line drawn from one focus point will bounce off the ellipse's interior wall and hit the other focus point. It also discusses the acoustic properties of elliptical rooms, where sound waves from one focus point are reflected and concentrated at the other focus point, allowing whispers to be heard clearly. The paragraph provides an example of the elliptical room built in the US Capitol, where John Quincy Adams reportedly took advantage of this acoustic phenomenon.

10:04

๐Ÿš— Explaining the Behavior of Objects During Acceleration and Deceleration

This paragraph addresses the puzzling behavior of objects sliding forward or backward during acceleration and deceleration in a car. It explains Newton's laws of motion, particularly the concept of inertia, and how the mass of an object determines the force required to move it. The paragraph also introduces the concept of air having mass and discusses how the relative densities of air and other substances (e.g., helium in balloons) affect their movement during deceleration.

15:05

โ›ต Investigating the Mechanics of Sailboat Propulsion

This paragraph investigates whether blowing on a sail can propel a sailboat forward. It debunks the notion of using a fan to blow on the sail, explaining that the force generated would push the boat in the opposite direction. Instead, it suggests that a fan or propeller pushing against water is more effective for propulsion. The paragraph also addresses the viral video of a person using a leaf blower and umbrella on a skateboard, revealing that the movement is due to an electric skateboard rather than the leaf blower and umbrella setup.

๐Ÿงต Exploring Surprising Facts About Ropes and Circumferences

This paragraph presents a mind-bending fact about the amount of extra rope needed to raise a rope encircling the Earth (or any other circular object) one foot off the ground. It demonstrates that regardless of the object's size, the extra length required is a constant 6.28 feet (or 2ฯ€ feet). The paragraph provides visual explanations using squares and a basketball to illustrate the concept and shows that the radius of the circle cancels out in the mathematical formula.

๐ŸŽ’ Evaluating the Claims of a 'Floating Backpack' Kickstarter

This paragraph examines the claims made by a Kickstarter project for a 'floating backpack' that allegedly reduces impact forces by up to 86%. It discusses the arguments for and against the effectiveness of such a design, considering factors like the potential reduction in vertical movement of the load and the added weight of the suspension system. The paragraph also details the author's personal experience testing the backpack on different terrains, concluding that while it may be beneficial on flat, predictable terrain, it is not worth the trade-offs on rough, sporadic hiking terrain.

๐ŸŒ Investigating the 'Coriolis Effect' and Debunking the Equatorial Water Drain Myth

This paragraph explores the 'Coriolis effect,' which causes weather patterns like hurricanes and cyclones to spin in opposite directions in the northern and southern hemispheres, respectively. It explains the underlying physics behind this phenomenon and how it could theoretically affect the draining of sinks and toilets differently in the two hemispheres. However, the paragraph ultimately debunks the popular myth that water drains in opposite directions on either side of the equator, revealing that a tourist demonstration claiming this is a scam achieved through a subtle twisting motion during pouring.

Mindmap

Keywords

๐Ÿ’กHemisphere

A hemisphere is one half of a sphere, such as the Northern or Southern half of the Earth. The video explains that the Moon appears upside down in the Southern Hemisphere compared to the Northern Hemisphere due to the perspective from different parts of the spherical Earth. For example, 'the moon in the sky, looks like this in the Northern hemisphere, like in Canada. But it looks like this in the southern hemisphere, like in Australia. It's upside down!'.

๐Ÿ’กEllipse

An ellipse is a closed, curved shape resembling an oval or elongated circle. The video demonstrates that an ellipse has two focus points, where any straight line from one focus will reflect off the ellipse's interior and hit the other focus. This property allows elliptical rooms to transmit sound efficiently between the two foci. For instance, 'If you build an actual full sized room, in the shape of an ellipse and then you stand at one focus point, you can hear even the faintest whisper from anyone, standing at the other focus point, even hundreds of feet away'.

๐Ÿ’กNewton's Laws of Motion

Newton's Laws of Motion describe the relationship between an object, the forces acting upon it, and its motion. The video invokes Newton's First Law (objects at rest tend to stay at rest) to explain why items slide forward during braking. It also uses Newton's Second Law (force is proportional to mass and acceleration) to demonstrate how the mass of air affects balloon movement during acceleration. For example, 'Newton's first law in action, which basically says all stuff is kind of lazy and wants to stay still, unless a force comes in and tries to move things'.

๐Ÿ’กCoriolis Effect

The Coriolis Effect is the apparent deflection of objects (like air or water currents) moving across the Earth's surface due to the planet's rotation. The video explains how this effect causes different spin directions for hurricanes and drains in the Northern vs. Southern Hemispheres. However, it debunks the myth that regular sinks and toilets exhibit significant Coriolis effects. As stated, 'The water is flowing clockwise due to the earth's rotation. The water is going counter clockwise because I'm in the northern hemisphere. It's real!'.

๐Ÿ’กCircumference

The circumference is the distance around the outside of a circular object or shape. The video presents a surprising fact that the extra rope length needed to raise an existing rope one foot above the Earth's circumference is only 6.28 feet, regardless of the circle's size. This counterintuitive result stems from geometrical reasoning, as exemplified: 'The circumference of the earth is 131 million feet. And yet you only need this much extra rope to lift the whole thing, a foot off the ground all the way around'.

๐Ÿ’กInertia

Inertia is the tendency of an object to resist changes in its state of motion. The video uses inertia to explain why helium balloons move backwards when braking in a car - the more dense air rushes forward due to its inertia, forcing the lighter balloon in the opposite direction. This concept is illustrated through an analogy: 'It's almost more like the heavier, more dense thing, in this case, the water, rudely cuts to the front of the line, forcing the poor ping pong ball up and out of the way'.

๐Ÿ’กSailboat Propulsion

Sailboat propulsion refers to the mechanisms by which sailboats are driven forward using wind power. The video debunks the idea that blowing air into a sail can propel a boat, demonstrating instead that effective propulsion requires redirecting air/water flow in the opposite direction, similar to how a propeller works. As stated, 'a fan actually sort of does work to move a boat forward, you just have to lose the sail and point it the other way. But at that point you might as well, just take that same fan and stick it underneath the boat, so you could much more effectively push, against the heavy water instead of just air'.

๐Ÿ’กScientific Method

The scientific method is a systematic approach to investigating phenomena, acquiring new knowledge, or correcting previous conjectures. The video employs the scientific method by formulating hypotheses, designing experiments or observations to test them, and drawing conclusions based on the empirical evidence. For instance, the video follows this process to evaluate claims made by a Kickstarter campaign about a 'floating backpack': 'So as a firm believer in the scientific method, I ordered one myself. And then went hiking for a few miles, with a normal backpack and then put the exact same amount of weight in the hover glide backpack to qualitatively compare the difference'.

๐Ÿ’กPassion for Learning

A passion for learning refers to an innate curiosity and enthusiasm for acquiring new knowledge and understanding the world around us. The video promotes cultivating this passion, positioning it as a core motivation for the host's work in science communication. It also frames the company CrunchLabs as a tool for nurturing this passion through hands-on learning experiences. As stated, 'It's a new year, which means it's a great time, to invest in that passion for learning, because that passion is not only the main driver for why I make these YouTube videos, but it's also why I created CrunchLabs'.

๐Ÿ’กSTEM Education

STEM is an interdisciplinary approach to education that integrates the fields of Science, Technology, Engineering, and Mathematics. The video touches on STEM education through its explorations of physics concepts and engineering principles. It also positions the CrunchLabs product as a tool for fostering interest and skills in STEM subjects among children, noting that 'more than three out of four parents said their child gained a new passion around STEM and engineering after getting the build box'.

Highlights

The moon appears upside down in the southern hemisphere compared to the northern hemisphere due to the Earth's spherical shape and the observer's perspective from different positions on the globe.

An ellipse's focus points have the unique property that any line originating from one focus point and reflecting off the ellipse's interior will pass through the other focus point, making elliptical rooms ideal for acoustics and eavesdropping.

The air around us has mass and density, which causes lightweight objects like balloons to move in the opposite direction of the denser air when a force is applied, as demonstrated in a car slamming on the brakes.

Blowing wind onto a sail does not effectively propel a boat forward; instead, a propeller pushing against the water is more efficient for propulsion.

The CrunchLabs subscription service delivers monthly toys and educational videos to teach physics and engineering principles through hands-on learning experiences.

Adding extra rope to raise a loop of rope one foot off the ground requires only 6.28 feet of additional rope, regardless of the loop's size or the object's circumference.

A Kickstarter campaign claimed to have invented a backpack with a suspension system that reduced impact forces by 86%, but practical testing revealed mixed results depending on terrain and walking cadence.

The Coriolis effect, caused by the Earth's rotation, can influence the direction of swirling water and weather patterns, but its impact on small sinks and toilets is negligible.

A popular tourist demonstration falsely claims that water drains in opposite directions on either side of the equator, but it is revealed to be a simple magic trick involving a subtle twisting motion when pouring the water.

The transcript emphasizes the importance of understanding the scientific principles behind various phenomena and debunking common misconceptions through practical demonstrations and experiments.

The transcript uses engaging storytelling and relatable examples to explain complex physics concepts in an approachable and entertaining manner.

The transcript promotes critical thinking and the scientific method by encouraging viewers to question assumptions and seek evidence-based explanations.

The transcript highlights the potential for science education to be both educational and enjoyable, combining hands-on activities with theoretical explanations.

The transcript emphasizes the importance of practical application and real-world testing in addition to theoretical understanding.

The transcript aims to inspire a passion for learning and understanding the principles behind everyday phenomena.

Transcripts

00:00

I'm about to plug in this fan to test whether blowing on this sail

00:03

will move the boat forward.

00:04

And then I'm traveling 4000 miles to the equator

00:07

where I'm actually standing in both the northern and southern hemispheres,

00:11

because this line here is the equator, and I'm here to investigate

00:15

whether or not this demo for tourists is a scam.

00:18

Basically, they pour water in this basin and on the north side of the equator,

00:22

it seems to swirl and drain counterclockwise,

00:24

but just a few feet away in the southern hemisphere.

00:26

The water seems to drain in the exact opposite direction.

00:29

It's sort of like how you also might have heard

00:31

toilets flush in opposite directions on different sides of the equator.

00:34

And we're here to uncover the truth.

00:36

But I'm not stopping there because today we're going to investigate

00:39

six other physics and engineering puzzles using simple demonstrations as we go.

00:44

Because our goal by the end of this video is for you

00:46

not just to know the right answers, but more importantly

00:49

for you to understand and why they're the right answers.

00:51

To kick things off.

00:52

Speaking of Hemispheres

00:54

did you know the moon in the sky

00:55

looks like this in the Northern hemisphere, like in Canada.

00:58

But it looks like this in the southern hemisphere, like in Australia.

01:02

It's upside down!

01:04

And while that is a fun fact, it's even more fun to understand why.

01:07

And this is why

01:08

As we all know, the Earth is...

01:11

a sphere.

01:12

So if you were Superman standing at the North Pole

01:14

in the Northern hemisphere, you'd look like this.

01:17

But if you were

01:17

Thor standing in the southern hemisphere in Antarctica, you'd look like this.

01:21

Now, of course, the moon over here orbits around the earth

01:25

like this, and I'm going to add an arrow to it to help us with orientation.

01:29

And so to the Superman at the North Pole

01:30

That arrow would point up, but from the perspective of Thor at the South Pole

01:35

That arrow would point down from his perspective.

01:38

And now I know what you're thinking.

01:39

If all that's true, then which way would the arrow point?

01:42

If you're Spiderman, standing here at the equator.

01:45

Well, according to our model here, it should be sideways

01:48

and sure enough, here in Ecuador, at the equator.

01:51

I'm happy to report that the moon does, in fact, appear to be sideways

01:56

For fun fact two of seven.

01:57

If you just stick

01:58

two pins into some cardboard like this and then connect them with a string

02:02

and trace it out, you get my favorite geometric shape...

02:05

an ellipse!

02:06

But there's something really special about these two pinholes.

02:09

They're called the focus points.

02:10

And any straight line you shoot out in any direction from one of the points

02:14

will bounce off the wall of the Ellipse and always hit the other focus point.

02:18

And here's proof because I've got a laser pointer

02:20

at one focused point, a ball of wax at the other,

02:23

and a mirrored surface all along the interior wall.

02:25

And now you can see, no matter which way I point the laser,

02:28

it always bounces off and lights up the wax.

02:31

But here's the really cool part.

02:33

If you build an actual full sized room

02:35

in the shape of an ellipse and then you stand at one focus point,

02:37

you can hear even the faintest whisper from anyone

02:40

standing at the other focus point, even hundreds of feet away,

02:43

because all the sound waves bounce right back to your ears

02:47

in fact,

02:47

this actual ellipse shaped room was built by John Quincy Adams

02:51

in the US Capitol building.

02:52

And legend has it, he was a master at anticipating the moves

02:55

of his opponents, plotting against him on the opposite side of the large hall.

02:59

And now that you know the physics involved,

03:00

it should come as no surprise that John Quincy Adams

03:03

conveniently placed his desk right on top of this leftmost focus point.

03:07

Next up at number three,

03:08

everyone knows when you slam

03:09

on the accelerator pedal in a car, the stuff in slides backwards.

03:13

And then when you slam on the brakes, the stuff inside just keeps moving

03:17

forward, including you, by the way

03:19

which is why we were seatbelts.

03:21

So then why the heck when I'm driving to the birthday party

03:24

and I have to slam on the brakes

03:26

does the cake slide forward?

03:28

But the balloons actually move backwards?

03:30

Now as for the cake sliding forward

03:32

Well, that's just Newton's first law in action,

03:35

which basically says all stuff is kind of lazy and wants to stay still

03:39

unless a force comes in and tries to move things.

03:42

And then Newton's second law tells us that the more you weigh

03:45

and the more mass you have, the more force is required to even get you to move.

03:49

But here's the thing we sometimes forget.

03:51

The air around us is a fluid and it also has mass.

03:55

It weighs something.

03:57

This is why air pressure is a thing.

03:59

There's tons of air molecules

04:01

stacked up above us and they each weigh just a tiny bit.

04:04

So we are like at the bottom of this air molecule dogpile.

04:08

This is why your chip bag expands when you head up to the mountains.

04:12

It's because it's moved up the dogpile.

04:14

Now there's less air above it, weighing down, pushing in on all sides.

04:18

And for a little proof, here's a simple demonstration

04:21

that the air molecules around us do actually weigh something.

04:24

When I throw this balloon at the sign, it moves,

04:26

but it doesn't quite knock it over.

04:28

Now, all I'm going to do is take that exact same balloon and just add air.

04:32

That's it.

04:33

Everything else is identical and unchanged.

04:35

And yet now, it bonks the sign over.

04:38

So that means we increased the mass only by adding some extra air.

04:43

Because again, Newton's

04:44

second law states

04:46

the heavier, the more massive a thing is

04:48

the better it is at bonking things over.

04:50

So in the car, when you slam on the brakes

04:52

itโ€™s not just the stuff in the back that has mass that wants to keep moving,

04:56

but all that invisible air does too.

04:59

So the air itself also sloshes forward when I slam on the brakes.

05:03

And since that air is more dense than the helium gas in the balloon,

05:06

the lightweight balloon gets forced backwards.

05:09

And that's what we'd expect, right?

05:11

We say a helium balloon floats in air

05:14

or this ping pong ball floats in water

05:17

but it's almost more like the heavier, more dense thing

05:20

in this case, the water

05:21

rudely cuts to the front of the line

05:23

forcing the poor ping pong ball up and out of the way.

05:27

In fact, you can see if we lay this jar on its side.

05:29

The same thing happens as in the car.

05:32

When I give the jar a push,

05:33

the water sloshes back, which forces the ping pong ball forward

05:37

and then when it stops

05:38

the water sloshes forward, forcing the ping pong ball back

05:42

then for number four, we're back here on the lake

05:44

to figure out if sailboats move by having wind blow in their sails

05:47

Why don't they just get a big old fan like this

05:49

to power them through the water?

05:51

Sort of like the guy in this viral video who's using a leaf blower

05:54

pointing into an umbrella to scoot his way around on a skateboard.

05:58

Well, let's think this through with the simple demo of a fan

06:01

that's attached to this train car.

06:03

When I turn the fan on

06:04

and it blows air to the right, which way will the car go?

06:08

Well, of course it goes to the left because it's basically

06:10

cutting through the air and pushing it backwards,

06:12

which creates an equal and opposite reaction that pushes the train forward.

06:15

Just like an airplane propeller pushing air backwards, moves the plane forward.

06:19

It's so different than me standing on this skateboard

06:21

And when I push watermelons to the left, they push back on me

06:24

So I roll to the right

06:26

NATE! AGAIN!?

06:27

And so now let's place a brick here so this car can't move.

06:30

And then add a second car here with a sail.

06:33

Now, when I turn the fan on, which way will this cart move?

06:38

Of course, to the right.

06:39

Because all that fast moving air hits the sail.

06:41

It's like it's being bonked by all those tiny little watermelons.

06:45

So if we now remove the brick and this cart wants to move to the left,

06:48

and then this one wants to move to the right,

06:50

what'll happen when we connect them?

06:55

Nothing,

06:56

because it's a perfectly timed tug of war with each car

06:59

trying to move in opposite directions with the same amount of force.

07:02

A fan actually sort of does work to move a boat forward,

07:05

you just have to lose the sail and point it the other way.

07:08

But at that point you might as well

07:09

just take that same fan and stick it underneath the boat

07:13

so you could much more effectively push

07:14

against the heavy water instead of just air,

07:16

which is, of course, exactly what a boat propeller does.

07:19

And sure enough, when I plug it in, in real life

07:22

as you can see,

07:24

I don't go anywhere.

07:25

So then if we've totally debunked the idea of blowing your own sail,

07:29

then what about that guy with the leaf blower and umbrella on the skateboard?

07:32

Well, I've copied his exact same setup here, and I can confirm it

07:35

actually does work.

07:37

Yeee Hooo!

07:38

Yeee Haaa!

07:38

It just has nothing to do with the umbrella

07:40

or the leaf blower

07:41

and everything to do with the fact that this is an electric skateboard

07:45

with the battery stored right under here.

07:47

Exactly the same as you can see in a bunch of these shots from his video.

07:51

Now, before we get to the last three, including answering

07:54

if this demo for tourists is a scam, if you're like me and you love that

07:57

ah-ha moment when you learn something new

07:59

well, I got great news for you.

08:01

Let me guess. CrunchLabs?

08:02

I'm glad you said it, Jimmy. That's right.

08:04

Because packaging up that movement is why I created CrunchLabs,

08:08

where you get a super fun toy every month in the mail

08:10

that comes with a video

08:11

where I teach you all the juicy physics that make the toy work.

08:14

Mark won't say this himself,

08:16

but obviously he used to work at NASA and Apple.

08:18

He's one of the greatest engineers that you can ever find,

08:20

and he's specifically designing these boxes

08:22

teach you all the stuff he learned

08:23

He had this water gun that we made.

08:25

And you can flip a switch when you give it to someone else

08:27

and it shoots back at you.

08:28

I mean, that's awesome.

08:29

I've pranked you a couple times with the boxes, Jimmy.

08:31

I know.

08:34

So if you want to prank MrBeast

08:35

while experiencing

08:36

a bunch of those lovely ah-ha moments at the same time

08:39

It worked!

08:40

just visit crunchlabs.com

08:42

to learn more.

08:42

Yesss!

08:43

Now coming in at number five is the craziest fact I know

08:46

Imagine I just finished tying this rope all the way around the world,

08:51

but now I just found out

08:52

it was supposed to be a foot off the ground the whole way around.

08:56

So the question is how much more extra rope would I need to buy to add

09:00

to this rope to make that happen.

09:02

Now, you might be thinking double or even triple this amount, but

09:05

what if I told you you only need this much extra rope

09:09

6.28 feet to be exact.

09:12

Think about that.

09:13

The circumference of the earth is 131 million feet.

09:16

And yet you only need this much extra rope to lift the whole thing

09:20

a foot off the ground all the way around.

09:22

And what's even crazier is if you did this around a basketball,

09:25

it would be the exact same amount of extra rope.

09:28

Now the math is just some straightforward eighth grade algebra.

09:31

And you can see here

09:32

because the radius cancels out, it doesn't matter what size circle

09:36

you use, it always works out to two pi or about 6.28 feet of extra rope.

09:42

But if math isn't your thing, don't worry,

09:43

because if you just pretend the earth is a square,

09:45

it will immediately be obvious why the size of the object doesn't matter.

09:49

So if this is my initial rope

09:50

When I raise it off the earth

09:52

by one foot, you can see in each corner I only need two extra feet.

09:55

So eight feet total.

09:57

And just like with the basketball, youโ€™d still get the same answer

10:00

If you try it on a smaller four-sided shape like your TV,

10:03

which is pretty close to the 6.28 extra feet needed for a circle.

10:08

At number six, there was a Kickstarter a while back.

10:10

that claimed to have invented a floating backpack that reduced

10:13

impact forces by 86%.

10:15

Welcome to the Future of backpacking.

10:18

You've never seen a backpack that moves like this

10:20

or that lets you move like this.

10:22

And this motion isn't just for show.

10:24

By suspending the load, hoverglide reduces impact forces by 80 to 90%.

10:29

I really took an interest once I noticed

10:31

a lot of people in the comment section

10:33

were debating whether or not this would actually help.

10:35

So what do you think?

10:36

Is this a scam?

10:37

The case for it not being a scam is that when you wear a normal backpack

10:40

as you bounce up and down

10:42

with each step you take

10:43

you're working against gravity as you move that entire weight

10:46

up and down with you as well.

10:47

Sort of like pulling this weight up and down with a stiff rope.

10:50

But if the backpack was elastically suspended on a track, its own

10:53

inertia would tend to keep it vertically in the same spot.

10:56

So you can still bounce up and down while the pack wouldn't move

10:59

so itโ€™d be like replacing that stiff rope

11:01

with an elastic one at which point you can see it makes it a lot

11:04

easier on my arms moving up and down as the weight stays in place.

11:07

But the naysayers pointed out

11:09

all the pulleys, cords and extra frames to make the system work

11:12

is still an extra 4 pounds of weight.

11:14

And whether it's bouncing or not, you're still carrying four extra pounds

11:18

to the top of the mountain.

11:19

Plus, the video just shows the ideal use cases, and in real life

11:22

it probably wouldn't work that smoothly, hiking over rough terrain.

11:26

And I felt like both sides sort of had valid arguments.

11:28

So as a firm believer in the scientific method, I ordered one myself.

11:31

And then went hiking for a few miles

11:33

with a normal backpack and then put the exact same amount of

11:36

weight in the hover glide backpack to qualitatively compare the difference.

11:40

So far, I don't like it. Feels like it's, like, rocking me back.

11:44

Iโ€™m going to try jogging.

11:46

oh that feels good.

11:47

That's kind of the trick I feel like

11:49

if you hit the right cadence, it's magical.

11:51

if it's not the right cadence,

11:53

It's the opposite of magic. oh yeah. Now it's.

11:55

And then it gets out of sync, throws you literally off balance

11:59

So my verdict is that on flat, predictable terrain,

12:01

it can be beneficial.

12:03

But on any sort of rough, sporadic hiking terrain, it's just not worth

12:06

the extra weight in force from out of sync issues.

12:09

And for our final science challenge, we're back here at the equator

12:12

in Ecuador to see if this popular demonstration for tourists

12:16

is actually a scam.

12:18

Does the water really drain in opposite directions,

12:20

even just a few feet on either side of the equator?

12:23

And relatedly, do toilets also swirl in opposite directions

12:27

in the northern versus southern hemisphere.

12:28

Now, for the toilets, let me just debunk that myth out of the gate,

12:32

because if you look closely, the swirl direction is just

12:35

a function of which way the nozzles point, as you could see here.

12:38

And with any toilet you inspect yourself.

12:40

But what about sinks that have just a drain

12:42

like in the demo here where there are no nozzles?

12:45

Well, believe it or not, there's actually some truth to this idea

12:47

because of something called the Coriolis effect.

12:49

And it's the same reason you might have noticed weather patterns

12:52

like this spinning counterclockwise in the northern hemisphere,

12:56

in which case we call them hurricanes and clockwise

12:59

in the southern hemisphere, in which case we call them cyclones.

13:02

And the reason for this is pretty straightforward to understand

13:05

If you imagine you have a very big sink that spans from the equator

13:08

all the way up to the North Pole, In that case,

13:10

a single drop of water in the sink at

13:12

the equator here is going for a joyride really fast as the earth spins

13:16

and a drop of water near the middle is moving at a medium speed.

13:19

But a drop of water at the North Pole

13:21

isn't moving at all because it's right on the axis.

13:24

So now when you pull the plug on the sink

13:26

and the water moves towards the middle, the joyriding drop here is suddenly

13:29

moving faster than the slower water that was away from the equator.

13:33

So it gets out in front of the drain

13:35

and conversely, the drop at the North Pole

13:38

is now moving much slower than the water closer to the equator.

13:41

So it falls behind.

13:42

So when all the drops are affected this way

13:44

you naturally get a counterclockwise swirl just like a hurricane

13:48

where the eye of the hurricane is the low pressure zone like a drain.

13:52

Then of course, applying all this same logic to the southern hemisphere

13:55

would of course do the opposite, resulting in a clockwise swirl.

13:59

So does this mean that sinks do in fact drain

14:01

opposite in the northern and southern hemispheres?

14:04

Well, sadly, no, because the Coriolis effect is really only noticeable

14:08

The greater distance you're moving up or down from the equator.

14:11

So unless you have a five mile wide sink, or if you make the most perfect

14:15

of perfect conditions, like my friends Destin and Derrick showed,

14:19

The water is flowing clockwise due to the earthโ€™s rotation

14:22

The water is going counter clockwise because Iโ€™m in the northern hemisphere

14:25

Itโ€™s real!

14:26

this effect is way too small to have any meaningful impact

14:29

on the swirl directions of sinks and toilets,

14:31

at which point

14:32

it comes down to other factors like sink geometry

14:35

or the fact that the seemingly still water

14:37

was actually still barely moving around when the plug was pulled.

14:41

So then what about that tourist demo? Well,

14:43

if you play it back and look closely, you can see the end of his pour.

14:46

He does this subtle twisting motion so the water would just continue

14:49

to swirl in the direction of the twist.

14:51

So when he finishes the pour here,

14:53

he twists this way and the water continues swirling that way.

14:56

And then after moving the sink, allegedly over the equator,

14:59

he finishes his pour, twisting the opposite direction,

15:02

and then the water swirls in that opposite direction.

15:05

In fact, you can easily recreate this demo yourself at home

15:08

to see that by copying this method,

15:10

you can also easily get a whirlpool in both directions

15:14

and therefore it should come as no surprise that when I ask this question

15:17

does it work even like if I pour the water,

15:21

I was denied the opportunity to test and observe

15:23

on top of all that as the final nail in the coffin

15:26

If you actually look up the GPS coordinates of this place,

15:30

itโ€™s more than a football field away from the official equator,

15:33

which means we were actually in the southern hemisphere the whole time.

15:37

So instead of actual science, this is just an attempt

15:39

to take your money with nothing more than a lame magic trick

15:42

where the real magic is all that new juicy knowledge

15:45

I just wirelessly transfered through that screen youโ€™re watching me on

15:48

from my brain into yours.

15:52

It's a new year, which means it's a great time

15:54

to invest in that passion for learning, because that passion is not

15:57

only the main driver for why I make these YouTube videos,

16:00

but it's also why I created CrunchLabs

16:02

where we ship a really fun toy to your porch every month.

16:05

And not only do you learn how to build and think like an engineer,

16:08

but you learn the fascinating physics and engineering principles

16:11

that make the toys work.

16:13

Every month is a new principle, and the best part is just like

16:16

how you hopefully enjoyed watching this video.

16:18

It doesn't feel like learning because we're real good

16:21

at hiding the vegetables.

16:22

And what I mean by that is 87% of kids rate it an eight through ten

16:26

on a fun scale out of ten.

16:28

But also more than three out of four parents said their child

16:32

gained a new passion around STEM and engineering after getting the build box.

16:35

Yessss

16:36

On top of that, each month, your box

16:38

has a chance to contain the platinum ticket and if you get it,

16:43

Well then you coming out to CrunchLabs to build with me and my team for a day.

16:46

So if you want to invest in the superpower

16:48

of having a passion for learning, just go to CrunchLabs.com or use

16:52

the link in the video description to get your build box subscription today.

16:57

Thanks for watching.

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