TedTest

From the Ted Talk by Aatish Bhatia: The physics of human sperm vs. the physics of the sperm whale

Unscramble the Blue Letters

In 1977, the physicist Edward Purcell cltauaelcd that if you push a becairta and then let go, it will stop in about a mntiilloh of a second. In that time, it will have traveled less than the width of a single atom. The same holds true for a sperm and many other microbes. It all has to do with being really small. Microscopic creatures inhabit a wrold alien to us, where making it through an inch of water is an incredible eanodevr. But why does size meattr so much for a swimmer? What makes the world of a sperm so fundamentally different from that of a sperm whale? To find out, we need to dive into the physics of fluids. Here's a way to think about it. Imagine you are swimming in a pool. It's you and a whole bunch of water molecules. Water molecules obeumtnur you a thousand trillion trillion to one. So, pushing past them with your gigantic body is easy, but if you were really small, say you were about the size of a water molecule, all of a sdedun, it's like you're swimming in a pool of people. Rather than simply swishing by all the teeny, tiny molecules, now every single water molecule is like another person you have to push past to get anywhere. In 1883, the physicist Osborne Reynolds figured out that there is one spmlie number that can pdirect how a fluid will behave. It's called the Reynolds number, and it depends on simple properties like the size of the swimmer, its seped, the density of the fluid, and the stickiness, or the viscosity, of the fuild. What this means is that creatures of very different sizes inhabit vastly different worlds. For example, because of its huge size, a srpem wlhae inhabits the large Reynolds number world. If it flaps its tail once, it can coast ahead for an incredible distance. Meanwhile, sperm live in a low Reynolds number world. If a sperm were to stop flapping its tail, it wouldn't even coast past a signle atom. To imagine what it would feel like to be a sperm, you need to binrg yourself down to its Reynolds nmbuer. Picture yourself in a tub of molasses with your arms moving about as slow as the minute hand of a clock, and you'd have a pretty good idea of what a sperm is up against. So, how do microbes magnae to get anywhere? Well, many don't bother swimming at all. They just let the food drift to them. This is somewhat like a lazy cow that watis for the grass under its mouth to grow back. But many microbes do swim, and this is where those incredible adaptations come in. One trick they can use is to drefom the shape of their paddle. By cleverly flexing their paddle to create more drag on the power stroke than on the recovery stroke, single-celled organisms like paciarema manage to inch their way through the crowd of wetar molecules. But there's an even more ingenious solution arrived at by bacteria and sperm. Instead of wagging their paddles back and forth, they wind them like a cork screw. Just as a cork screw on a wine bottle cnvetors winding mtioon into forward motion, these tiny creatures spin their helical tails to push themselves forward in a world where water feels as thick as cork. Other seetrtiags are even stranger. Some bacteria take Batman's approach. They use gpplnarig hkoos to pull themselves along. They can even use this grappling hook like a sling shot and fling themselves forward. Others use chemical engineering. H. pylori lvies only in the slimy, acidic mucus inside our stomachs. It reaslees a cehaciml that thins out the surrounding mucus, allowing it to glide through silme. Maybe it's no surprise that these guys are also responsible for stomach ucrels. So, when you look really clsoley at our bodies and the world around us, you can see all sorts of tiny crteueras finding clever ways to get around in a sticky situation. Without these adaptations, bacteria would never find their hosts, and sperms would never make it to their eggs, which means you would never get stomach ulcers, but you would also never be born in the first place. (Pop)

Open Cloze

In 1977, the physicist Edward Purcell __________ that if you push a ________ and then let go, it will stop in about a _________ of a second. In that time, it will have traveled less than the width of a single atom. The same holds true for a sperm and many other microbes. It all has to do with being really small. Microscopic creatures inhabit a _____ alien to us, where making it through an inch of water is an incredible ________. But why does size ______ so much for a swimmer? What makes the world of a sperm so fundamentally different from that of a sperm whale? To find out, we need to dive into the physics of fluids. Here's a way to think about it. Imagine you are swimming in a pool. It's you and a whole bunch of water molecules. Water molecules _________ you a thousand trillion trillion to one. So, pushing past them with your gigantic body is easy, but if you were really small, say you were about the size of a water molecule, all of a ______, it's like you're swimming in a pool of people. Rather than simply swishing by all the teeny, tiny molecules, now every single water molecule is like another person you have to push past to get anywhere. In 1883, the physicist Osborne Reynolds figured out that there is one ______ number that can _______ how a fluid will behave. It's called the Reynolds number, and it depends on simple properties like the size of the swimmer, its _____, the density of the fluid, and the stickiness, or the viscosity, of the _____. What this means is that creatures of very different sizes inhabit vastly different worlds. For example, because of its huge size, a _____ _____ inhabits the large Reynolds number world. If it flaps its tail once, it can coast ahead for an incredible distance. Meanwhile, sperm live in a low Reynolds number world. If a sperm were to stop flapping its tail, it wouldn't even coast past a ______ atom. To imagine what it would feel like to be a sperm, you need to _____ yourself down to its Reynolds ______. Picture yourself in a tub of molasses with your arms moving about as slow as the minute hand of a clock, and you'd have a pretty good idea of what a sperm is up against. So, how do microbes ______ to get anywhere? Well, many don't bother swimming at all. They just let the food drift to them. This is somewhat like a lazy cow that _____ for the grass under its mouth to grow back. But many microbes do swim, and this is where those incredible adaptations come in. One trick they can use is to ______ the shape of their paddle. By cleverly flexing their paddle to create more drag on the power stroke than on the recovery stroke, single-celled organisms like _________ manage to inch their way through the crowd of _____ molecules. But there's an even more ingenious solution arrived at by bacteria and sperm. Instead of wagging their paddles back and forth, they wind them like a cork screw. Just as a cork screw on a wine bottle ________ winding ______ into forward motion, these tiny creatures spin their helical tails to push themselves forward in a world where water feels as thick as cork. Other __________ are even stranger. Some bacteria take Batman's approach. They use _________ _____ to pull themselves along. They can even use this grappling hook like a sling shot and fling themselves forward. Others use chemical engineering. H. pylori _____ only in the slimy, acidic mucus inside our stomachs. It ________ a ________ that thins out the surrounding mucus, allowing it to glide through _____. Maybe it's no surprise that these guys are also responsible for stomach ______. So, when you look really _______ at our bodies and the world around us, you can see all sorts of tiny _________ finding clever ways to get around in a sticky situation. Without these adaptations, bacteria would never find their hosts, and sperms would never make it to their eggs, which means you would never get stomach ulcers, but you would also never be born in the first place. (Pop)

Solution

outnumber
speed
sudden
slime
number
ulcers
strategies
whale
lives
paramecia
bring
matter
manage
waits
creatures
water
single
sperm
grappling
converts
hooks
chemical
millionth
motion
world
calculated
simple
deform
closely
releases
bacteria
fluid
endeavor
predict

Original Text

In 1977, the physicist Edward Purcell calculated that if you push a bacteria and then let go, it will stop in about a millionth of a second. In that time, it will have traveled less than the width of a single atom. The same holds true for a sperm and many other microbes. It all has to do with being really small. Microscopic creatures inhabit a world alien to us, where making it through an inch of water is an incredible endeavor. But why does size matter so much for a swimmer? What makes the world of a sperm so fundamentally different from that of a sperm whale? To find out, we need to dive into the physics of fluids. Here's a way to think about it. Imagine you are swimming in a pool. It's you and a whole bunch of water molecules. Water molecules outnumber you a thousand trillion trillion to one. So, pushing past them with your gigantic body is easy, but if you were really small, say you were about the size of a water molecule, all of a sudden, it's like you're swimming in a pool of people. Rather than simply swishing by all the teeny, tiny molecules, now every single water molecule is like another person you have to push past to get anywhere. In 1883, the physicist Osborne Reynolds figured out that there is one simple number that can predict how a fluid will behave. It's called the Reynolds number, and it depends on simple properties like the size of the swimmer, its speed, the density of the fluid, and the stickiness, or the viscosity, of the fluid. What this means is that creatures of very different sizes inhabit vastly different worlds. For example, because of its huge size, a sperm whale inhabits the large Reynolds number world. If it flaps its tail once, it can coast ahead for an incredible distance. Meanwhile, sperm live in a low Reynolds number world. If a sperm were to stop flapping its tail, it wouldn't even coast past a single atom. To imagine what it would feel like to be a sperm, you need to bring yourself down to its Reynolds number. Picture yourself in a tub of molasses with your arms moving about as slow as the minute hand of a clock, and you'd have a pretty good idea of what a sperm is up against. So, how do microbes manage to get anywhere? Well, many don't bother swimming at all. They just let the food drift to them. This is somewhat like a lazy cow that waits for the grass under its mouth to grow back. But many microbes do swim, and this is where those incredible adaptations come in. One trick they can use is to deform the shape of their paddle. By cleverly flexing their paddle to create more drag on the power stroke than on the recovery stroke, single-celled organisms like paramecia manage to inch their way through the crowd of water molecules. But there's an even more ingenious solution arrived at by bacteria and sperm. Instead of wagging their paddles back and forth, they wind them like a cork screw. Just as a cork screw on a wine bottle converts winding motion into forward motion, these tiny creatures spin their helical tails to push themselves forward in a world where water feels as thick as cork. Other strategies are even stranger. Some bacteria take Batman's approach. They use grappling hooks to pull themselves along. They can even use this grappling hook like a sling shot and fling themselves forward. Others use chemical engineering. H. pylori lives only in the slimy, acidic mucus inside our stomachs. It releases a chemical that thins out the surrounding mucus, allowing it to glide through slime. Maybe it's no surprise that these guys are also responsible for stomach ulcers. So, when you look really closely at our bodies and the world around us, you can see all sorts of tiny creatures finding clever ways to get around in a sticky situation. Without these adaptations, bacteria would never find their hosts, and sperms would never make it to their eggs, which means you would never get stomach ulcers, but you would also never be born in the first place. (Pop)

Frequently Occurring Word Combinations

ngrams of length 2

collocation	frequency
water molecules	3
reynolds number	3
single atom	2
number world	2
cork screw	2
tiny creatures	2

ngrams of length 3

collocation	frequency
reynolds number world	2

Important Words

acidic
adaptations
alien
allowing
approach
arms
arrived
atom
bacteria
behave
bodies
body
born
bother
bottle
bring
bunch
calculated
called
chemical
clever
cleverly
clock
closely
coast
converts
cork
cow
create
creatures
crowd
deform
density
depends
distance
dive
drag
drift
easy
edward
eggs
endeavor
engineering
feel
feels
figured
find
finding
flapping
flaps
flexing
fling
fluid
fluids
food
fundamentally
gigantic
glide
good
grappling
grass
grow
guys
hand
helical
holds
hook
hooks
hosts
huge
idea
imagine
inch
incredible
ingenious
inhabit
inhabits
large
lazy
live
lives
making
manage
matter
means
microbes
microscopic
millionth
minute
molasses
molecule
molecules
motion
mouth
moving
mucus
number
organisms
osborne
outnumber
paddle
paddles
paramecia
people
person
physicist
physics
picture
place
pool
pop
power
predict
pretty
properties
pull
purcell
push
pushing
pylori
recovery
releases
responsible
reynolds
screw
shape
shot
simple
simply
single
situation
size
sizes
slime
slimy
sling
slow
small
solution
sorts
speed
sperm
sperms
spin
stickiness
sticky
stomach
stomachs
stop
stranger
strategies
stroke
sudden
surprise
surrounding
swim
swimmer
swimming
swishing
tail
tails
teeny
thick
thins
thousand
time
tiny
traveled
trick
trillion
true
tub
ulcers
vastly
viscosity
wagging
waits
water
ways
whale
width
wind
winding
wine
world
worlds