Why Are Astronauts Weightless?
ฝัง
- เผยแพร่เมื่อ 10 ก.ย. 2024
- www.abc.net.au/...
I have been working with Catalyst on ABC1 to bring some Veritasium to Australian TV. In this segment I ask why astronauts in the space station are weightless. The most common answer is because there is no gravity in space. But of course there is gravity in space, especially where the space station is located (only about 400km from Earth's surface). So astronauts still experience a gravitational pull - it's just that they and the space station are in free fall so they are accelerating together towards the Earth. The space station doesn't crash into the Earth because of its orbital velocity - it's going 28,000 km/h so as it falls, the Earth curves away from it.
Thanks for actually explaining it, instead of doing what everyone else does and saying "It's because you're in freefall!" without giving any explanation whatsoever.
The trick to flying is fall, but miss the ground.
RIP Douglas Adams.
the trick is to fall with style
:PP
Well said.
the centrifugal force is complaining for not mentioning it
Hitchhiker's Guide to the Galaxyyyyyyyyyyyyyyyyy
"It's not flying, it's falling, WITH STYLE!" -Buzz Lightyear
Uhh, actually, woody said that. Not Buzz.
They actually both say it
Actually, Buzz said that. Woody said "That wasn't flying, that was-- falling with style."
Woody said it first buzz said it later not tryna be rude or anything but yeah
I would say underrated commented, but that would be overrated of me.
"The knack of flying is learning how to throw yourself at the ground and miss." - Douglas Adams
Now that's funny 😂😂
Richard Strosahl Isn't that a quote from The Hitchhiker’s Guide to the Galaxy?
That quote was in the book yes, which was written by Douglas Adams, which you probably knew
That quote was in the book yes, which was written by Douglas Adams, which you probably knew
+Richard Strosahl i thought exactly of that too :D
i love knowing the answers beforehand, i feel like a genius because of it
in the case of something orbiting, the acceleration is perpendicular to the velocity. This means it can change the direction of velocity but not its magnitude. For acceleration to cause a change in speed it must have a component in the same (or opposite) direction to velocity.
2) One important thing to consider is that the force of gravity cannot really be felt. The only reason we have a sense of weight is because for the most part, we are all experiencing forces that COUNTER the force of gravity. So when you stand on the ground, you are not feeling the force of gravity, you are feeling the force of the ground pushing you up (usually with an equal and opposite force of gravity). When in free fall, there are no countering forces, so you FEEL weightless. but you're not.
Play Kerbal Space program, easiest way to understand this.
lol so true
+niwcsc This, and get to know your apoapsis from your periapsis
I played
So true
Oh yea
As my physics lecturer would say "You are never weightless, you are however, normalforceless. It is this normalforcelessness that you call weightless. You cannot perceive weight"
i can
Now that's a masterpiece line
Your weight can be 0 but mass cant
Veritasium in simulated micro gravity is very creepy :P
If you are on your way to the moon, you really do reach a point where the Earth's gravity is negligible. Two Earth diameters away from Earth and your weight would be 4% of its present value (and the moon is roughly 30 Earth diameters away)
But then wouldn't you feel the gravitational pull of something else like the moon or the sun it's all bogus
@@damprotek Gravity is not something you feel directly. You feel gravity through a force that resists it, like an elevator, a rocket, a floor in a building, an airplane (that isn't falling), or the ground of the earth itself.
Every time the ISS "reboosts" itself to correct its orbit, the astronauts feel some resistance, and hence don't feel completely weightless at that moment in time.
@@gistfilm the velocity is constant, shouldnt come the time they would Stay on the "ground" of the space Station?
So, would I feel the exact same sensation here on earth if I were to, say, jump off of a building while inside some type of container? The "container" is just there so I don't feel the air resistance.
yeah actually, until the container hits terminal velocity it would effectively fall at the same speed as you so relative to the container you'd be weightless.
+KingHalbatorix Not exactly. You'd need to jump off a building in a vacuum; box or not. Being inside the box doesn't eliminate drag. The drag is just on the box now, and it would NOT be in free fall in air. It doesn't accelerate at 9.8 m/s² and then all of a sudden stop accelerating at terminal velocity; the acceleration would gradually decrease as the drag force increased until it reached zero - at which point you would feel like you were just sitting on a box on the ground.
What would actually happen is you would feel weightless at first (for a split second) and you would feel heavier and heavier until you reached terminal velocity and then you'd feel as heavy as you do on the ground.
Willoughby Krenzteinburg Interesting. Thanks for the explanation.
I hope you didn't tried it :o
Just go to a theme park and get on some of the rides! That's what it should feel like all the time. Then think about it and question if you believe they are actually out there. The orbits they use are .9G free fall , NOT 0G.
Such a simple concept, but did not know until I was about 50. Am 70 now. Why in the !* didn't one of my teachers back in the 1960s' spend just 3 minutes explaining. And this was when orbiting the earth was BIG news. Thank you Veritasium for filling some of the huge gaps.
Woah
I rarely see someone as old as you on this app(I am really sorry if it sounds rude)
I would love to be friends with you
no, a plane and a space station have very different orbits. Planes fly at 10 km, much lower than 300km and they fly through much thicker atmosphere, making faster flying (>27000 km/h) impossible. But yes if they could go fast enough they would orbit, with weightless passengers inside.
um, we don't need gravity to digest food. Smooth muscle lining your digestive tract keeps the food moving.
planes don't go fast enough to "orbit". You are a little lighter 1) because you are 10km further from Earth's surface and 2) because some of your weight force is used to accelerate you in circular motion as you pass over Earth's surface.
Thanks, Kerbal Space Program.
Lol I was thinking the same thing😀
Haha same here
I love the direction this show is going!! I have a feeling I'm going to be a long time subscriber!!
Just out of curiosity, I calculated the orbital velocity at 10km from earth, and got 7900 m/s or 28440 km/h or 7.9 km/s. I found it surprising how close that is to the ISS's speed at 7706.6 m/s (also 27744 km/h or 7.71 km/s)
The "need to know" is the best tool to knowledge. I see that he's explained just enough to whey the appetite for more.
I enjoy your videos, thank you for explaining in simple terms. Great Job!!
There may be a distance at which our best intruments could no longer detect the gravitational pull of earth, but technically the pull of gravity extends to infinity with the force decreasing proportional to the square of the distance.
lol that urge to correct the wrong answers of the people.
Oreobility lol that urge to ask the wrong people to collect the wrong answers
the urge to defend the wrong people for being wrong, instead of acknowledging that he's teaching them something
The first video I watched and now I have been his subscriber for more than 2 years. Just revisiting old topics
Lol @ u floating. That was great as usual though :D
well the space station is not that much further as a proportion of orbital radius, plus the velocity is inversely proportional to the square root of r so I think the similarity makes sense.
they turn the rocket on its side once it's left the densest part of the atmosphere
That's why railguns putting things into orbit on Earth isn't a good idea.
"How much of the atmosphere would you like to put the payload through?" Railgun- Yes
I've always loved that pseudo-weightlessness you get during a massive drop on roller coasters or something else of the sort.
Shut the hell up Drew Jones
Hi,
Recently I saw the movie Gravity, I really liked it but something is really bothering me about the movie.
There is a scene where the satellite debris hit the Hubble Space Telescope and the astronaut gets loose in space, in this case, because of the gravitational forces, whouldn't the astronaut start falling into earth?
This Really Bothers Me So I Will Be Very Thankful If You Could Answer Me.
The ISS goes around the world in 90 minutes, so does the astronaut - they have a speed of 25,000 miles per hour. If the astronaut jumps off at 10 mph, she is still traveling at 25,010 mph, so she goes around the world. 90 minutes later she is only 15 miles in front of the space station and will travel like that for a year or more until air friction slows her down enough to fall to thicker air where she will burn up as a meteor.
there are lots of places far from big masses so the gravitational force on mass would be basically zero there.
stopped at 1:31 .. the space station is actually free-falling... so when astronauts are floating... they are actually free falling like sky diving.. I don't know if the exact terms as to why.. but I know its free falling... let's see if I was right.
I thought the centrifugal force of orbiting neutralizes the gravitational force. it's half right, the actual phenomenon is the same but seen at a different perspective.
nextlifeonearth Nope. You've actually mixed up the different frames of reference yourself. If gravity were treated as a force that shows up in one frame of reference, then the corresponding centrifugal force only shows up in the rotating frame of reference. The two NEVER shows up in the same frame of reference and "cancel out". This is how, for example, spinning a bucket of water won't end up having water everywhere - you apply the centripetal force in your frame of reference. In the rotating frame of reference of the water, there is no centripetal force - only centrifugal force. Think about it - by your faulty analysis, if the two cancels out, the water in the bucket is weightless - it wouldn't stay in the bucket at all (and you wouldn't feel the weight of the bucket)!
All this is moot anyways, because gravity isn't really a force. All orbits are inertial paths, meaning there are no forces acting on you.
Narcissist86 you're either an idiot or really bad informed, no offence. The gravitational force of the earth would be the arm holding the bucket(satellite) and this is present, believe me. If you turn a bucket slower the water would be weightless in the bucket. (even slower and it'll get wet al over) if the satellite goes faster it'll move away from the earth(more outward centrifugal force, more acceleration, moving away) should he go slower, it'll fall to earth.
nextlifeonearth Sorry, ad hominem attacks don't work, especially when it's clear you don't know what you're talking about. I'm going to guess you have only about high school education on the matter, so it's really ironic when you call someone an idiot when there is such a large knowledge gap. But you know, you need to have SOME knowledge to know the limits of that knowledge.
As I said before, in general relativity orbits are geodesics - inertial paths through space. There are no proper forces whatsoever. So there is no need to get bogged down on wrong-minded discussions on centrifugal forces.
"If you turn a bucket slower the water would be weightless in the bucket."
Wrong. Please read up on centrifugal forces, and how it never appears in the same frame of reference as centripetal force. They never appear in the same frame to "cancel out". It's almost like you've never done free body diagrams in rotating reference frame before!
Narcissist86 calling it weightless might have been wrong, I meant relative to the bucket it would appear weightless and because of the centrifugal force it does not drop down, I asked a professor in physics if you were right, he said you were kinda right but so was I so don't try to disregard different views for the same thing. You might have understood me wrong and I apologise for calling you an idiot, but I don't like being called wrong when there are no real arguments opposing my theories.
He loves playing astronaut. Look at his expression. It's adorable.
U GOT SECOND LIKE FROM ME AFTER 8 YEARS
Great video! I have a follow-up question: if they are constantly accelerating towards the earth, shouldn't their velocity be increasing? Is it?
Interesting question. I don't know the answer either but is the answer somewhat similar to why the Earth's rotation around the sun and the moon's rotation around the earth are not speeding-up?
Acceleration doesn't just mean that things are speeding up or slowing down, it can also means change of direction.
After hearing it, this actually makes a whole lot more sense than what I thought was happening.. good1!
Hey, i really like ur videos, u make things easy to understand, can you post a video about cellular systems, no other video can be as helpful as yours!!
so its falling towards the earth but because they are falling so fast it falls away from the earth and the gravitational pull keeps it at the same distant away from the earth,
The subtitles at 0:37
Who wrote those😂
🤣🤣
Ya,I also commented that!LMFAO!
?
Great video. One thing that was not explained is that the space station's sideways velocity is able to prevent it from falling to Earth due to there being very little resistance from the atmosphere. If the space station were much closer to Earth, it would slow down due to atmospheric resistance and fall to Earth. It is both the sideways velocity and the lack of resistance that prevents the space station from falling to Earth.
did no one see the hidden message n the subtitles?
And like I said in my very first post explaining this, it is not velocity and gravity that are in balance like you said. It is the inertia/momentum and gravity that are in balance.
Finally a video I knew all the answers for XD
Ikr
lol me too
Those 2 guys in green tops are so cute, I could hardly concentrate, haha. Great video though. My fave so far. :)
How come I can't answer some peoples questions in the youtube section because there is no button?
+MrBaronmoll I think you can deactive replys. Another reason would be that the comments are too old
Wow! this is the first question Veritasium has asked which i got wroong, this is awesome!
2:45
Sneaky audio cut ;)
What Ciaran said is right. I'd just like to add this. It's surface tension will pull the molecules together and form the most efficient shape, and a sphere has the least amount of surface area for a given volume, so a sphere is the most efficient shape.
YES I KNEW THIS BRFORE THIS VIDEO! I feel smart
Actually, while it might come off that way, he has done studies that show people learn more via video when it is presented in the way he does here (presenting the misconceptions people have to begin with, then correcting them). His name is Derek Muller. Read up on him. It's actually quite interesting. His thesis was on this. I think it is titled "Designing Effective Multimedia for Physics Education". In other words, he has done his homework and is helping people. He deserves props.
i havnt read the comments but its considered zero g not zero gravity
+Ben Capella It's literally the same thing. There is as much difference between zero g and zero gravity as there is between ABS and anti-lock brakes.
simple enough for ya
+Willoughby Krenzteinburg nah he's right g is a force and there is no force on the astronaut however there is constant gravity on the astronaut.
TONY BUI g is accelerarion, bud. G-force is a unit of apparent acceleration. 1 G-force is an apparent acceleration of 9.8 m/s^2. When standing on the surface of the Earth, your are experiencing 1 G-force. It's not a force. It's the apparent acceleration felt.
When in free fall, you experience zero G-forces. You feel zero apparent accelerations. This is what "zero g" and "zero gravity" mean. This is simple fact.
You people don't have to accept this, but you're wrong if you dont. It's really of no consequence to me either way.
+Willoughby Krenzteinburg g is not force. g is gravitational field strength or to put it in other words, force per unit mass or to put it in even simpler words, acceleration due to gravity. If a body is experiencing a force of 1g, it means that the body is accelerating at a rate of 9.81 m/s2.
Really awosome video!! Just perfect. I loved you practising the concept of science-teaching video and bringing it solidly into reality. That was a perfect ,complete scene showing the whole theoritical concept.(Y) APPRICIATE!!
This is one of the first times watching these videos that I have genuinely learned something that I didn't at least have a marginal idea of.
Velocity is a vector quantity with a magnitude (speed) and a direction. A change in direction is just as much an acceleration as a change in speed is, and objects in orbit are constantly changing direction. You could also call this centripetal acceleration and it is consistent with universal gravitation. For example, the acceleration of a falling body at the surface of the Earth is 9.8 m/s^2. A hypothetical object in orbit right at the surface has the same acceleration.
After listening to these people's answers, I now have no hope for humanity.
Lol
this is alot better than other videos ive seen i kinda stopped watching because he would spent 5 mins asking people questions and getting wrong answers then finally after 5 mins get the answer. but this is good pace few answers and then he answers it
food are not floating since there is low amount of space in the stomach, its pretty tight in there. It just expand on the amount of food that get in.
yeah it affect digestion since the effect of the lack of gravity actually make foods moving very very slower through the body.
They don't shower, they use a special kind of soap that don't need water. if i remember right, its some kind of gel.
Water is vital up there, and cost a lot to carry. so they drink it instead
Acceleration is any change in speed or direction of movement. So think of the spacestation as constantly falling towards Earth and just missing the ground. It keeps changing its direction because when it gets to the other side of the Earth, it's now being pulled a different direction. That means it has "accelerated" because it's being pulled in a different direction.
As documented in Section 6.14.4 of NIST NCSTAR 1, these collapse times show that:
"Since the stories below the level of collapse initiation provided little resistance to the tremendous energy released by the falling building mass, the building section above came down essentially in - ZERO GRAVITY - as seen in videos. As the stories below sequentially failed, the falling mass increased, further increasing the demand on the floors below, which were unable to arrest the moving mass."
So what would it be like for an astronaut if they were in interstellar space?
I think that the centrifugal force is compensating the gravity. It is the same thing in the end, but i consider it is easier to understand
That moment when you watch his videos and say to yourself:
From now on, I will try to do my best to listen and understand what the teacher talks about in Physics lessons,
So one day we will meet, and I would (hopefully) answer almost all of his questions right!
Yes, there is still some force when "swimming", I'm just not sure if it's getting you anywhere within a reasonable amount of time.
Thanks.
They are constantly accelerating toward the center of Earth. That is the force vector, so the acceleration vector points toward the center of Earth as well. The important thing to understand is that acceleration is a vector quantity, which means it has a magnitute (velocity) and a direction. This means that a change in direction is just as much an acceleration as a change in velocity is. At any given instant, the ISS is accelerating (changing direction) toward the center of Earth.
Pretty much. The ISS however is in a low earth orbit where the atmosphere is still present, even if extremly thin, and the friction causes it to slow down very slowly. That's also why it has to make slight orbit adjustments every once in a while. But it would take ages for it to actually hit the earth(or burn up during reenter in a thicker part of the atmosphere)
Acceleration is a change in velocity. Velocity is a vector quantity, which means it has both speed and a direction. Objects in orbit are constantly changing direction (since they are orbiting in a circular trajectory), therefore they are accelerating. A change in direction is just as much an acceleration as a change in speed is.
To answer your question, if you were to drop a rock from an elevation equal to where the ISS orbits, the acceleration of the rock, and the acceleration of the ISS would be identical. It's just that the rock accelerates in a linear fashion (acceleration only affects speed), and the ISS is accelerating angularly (centripetal acceleration), but the accerations are the same. If you ignored air resistance, and put something in orbit near the surface, its centripetal acceleration would be 9.8m/s².
That's not what I said. You can look at centripetal acceleration as an acceleration in the direction vector. Since acceleration is a change in velocity, and velocity contains a speed AND a direction, then a change in direction is also an acceleration. ANY change in speed, direction, or combination of the two is an acceleration. The ISS, although not constantly gaining speed, is constantly changing direction, therefore it is constantly accelerating.
The first cosminc speed would be the velocity required to orbit the Earth right at the surface. It obviously ignores any drag. The second cosmic speed is the escape velocity of the Earth, and the third cosmic speed is the escape velocity of the sun.
I knew everything in this video already, BUT, I have one question. If the astronauts float because they are falling, but don't crash because they are moving sideways...why do they still float in a geosynchronus orbit (the shuttle has done this several times)? I know they are still moving sideways, but much slower, so the floating sensation should at least be greatly reduced.
Acceleration is also a vector quantity, with a magnitude and direction as well. Objects in orbit are constantly accelerating (changing direction), and the acceleration vector is pointed toward the center of the Earth. This is why you say that objects in orbit are constantly accelerating toward the center of the Earth.
Forget about speed, force is caused by acceleration. If the vessel you are in is accelerating at the same rate and in the same direction as you, then you will appear weightless. This is true for orbiting the earth at any height, and it's also true for traveling back down to the earth. If you are in an elevator that suddenly breaks loose and free falls to the ground, you will appear to be momentarily weightless within the elevator.
Centripetal force is a force that acts inward and is responsible for redirecting objects into a circular path, and the force is pointing directly toward the center of rotation (or curve). If you spin a ball with a string around your head, the string exerts a centripetal force on the ball that continually redirects its path toward your hand (which acts as the center). The string remains taut because of centrifugal force, which is just the inertia of the ball wanting to continue straight. cont..
They are still in a state of free fall. When you throw a ball in the air, that ball is free falling for the entire flight (ignoring air resistance). If the only force acting on a body is gravity, then it is in a state of free fall. The ball is free falling on the way up as well. It is accelerating toward the Earth the entire time, and the astronauts are accelerating toward the Earth for the entire trip to the moon - and slow down all the way there.
Think of a change in direction as a change in speed along a single axis. The net speed over all 3 dimensional axis doesn't change, but the speed along certain axis do change. This is all a change in direction is. It is a change in speed along a specific axis. You are making this a lot more complicated than it needs to be!!!
One of your best videos... together with that one form the park, with the huge granite ball.. Congratulations from Europe !!! CARRY ON !
I'm not an expert by any means, but I believe that centripetal force is the actual reason why they are orbitting the earth and are weightless. Since they're traveling with a horizontal velocity, the earth pulls them toward itself. This creates the orbit, which is (I think) a form of centripetal force. Since the velocity and gravitational pull are nearly equal, there is no push to the outside of the circle; otherwise the space station would sling out into space in the horizontal direction.
Fabulous explanation! I watched 10 videos before this but only you made me understand. You've earned yourself a new subscriber :)
Also worth noting is I am not implying that if an elevator is moving, it is accelerating. It is only accelerating when starting or stopping; not the entire ride.
You do not gain weight in a rising elevator or lose weight in a descending elevator. You FEEL heavier or lighter, but your weight is unchanged. The reason you feel heavier or lighter when the elevator is accelerating is inertia (an object's resistance to change in motion).
It came from rocket engines and boosters on liftoff and transmission into orbit. Once the orbital velocity is achieved, inertia maintains the velocity for the most part. There isn't much drag where they orbit, so they have no reason to 'slow down'. That's not to say there isn't any drag whatsoever because there is. Every so often, there are relatively minor burns that are required to correct for the little drag that does exist, but for the most part, once you get it going, it keeps on going.
It's falling. You are falling back to the Earth. But the ship is moving with you as you fall.
9.8 is the rate of acceleration for objects near the surface of the Earth. It decreases as the distance increases. It's around 9 m/s² (or a little less) for the space station. I think your real question though is along what JenyApple asked though. How can you say it is constantly accelerating if it's not really getting any faster? That is because acceleration is a change in speed OR direction (or combination of both). In other words, a change in direction IS an acceleration.
That is ...the trajectory of fall matches with the curve of earth and it continuously falls
To us (our feeling) weight is the push of the earth ground or other objects standing on it towards us that is stopping us - not letting us to move (fall) any further.
The mg force is used as centripetal force.
I mean by drawing a force body diagram, we can get mg = mv²/r
shuttles which supply the ISS also sometimes use a booster to increase the horizontal velocity of the station, keeping it in orbit. Also you assumed I did not understand even though you did not know why I thought he was wrong and as you can see I understand all of this very well.
Wow, love your channel, your doing a great job of explaining science to people, well done :o)
My guess is yes. In such a hypothetical situation the center of mass of the cube would still be in the center of the object so it would still orbit the same.
I understood the science behind this even before this video, but I never made the connection. I always thought it was because they were beyond Earth's gravitational pull! Mind = Twisted!
Your weight is a measure of mass times the acceleration "due to gravity". The resulting force due to an accelerating elevator has nothing to do with gravity, therefore your weight has not changed. The net force acting on your body is your weight plus or minus the force due to the acceleration of the elevator (depending on direction of acceleration). Your weight doesn't change. In other words,
Force = (m*g) +/- (m*a) where a is the acceleration of the elevator and of course (m*g) is weight.
The thinner the atmosphere, the faster an aircraft can go. For example, a 747-400 cruising at FL380 will be flying at a faster TAS than if it was flying at say, 10,000ft and require less thrust. For a 747, each of the 4 engines would have to provide some 1,500,000 pounds of thrust each for the occupants to be at a high enough speed to feel weightless in orbit.
@everyday420ful. They are accelerating at a constant rate, but their speed is not changing all that much. Acceleration is a change in velocity, and velocity is a vector quantity which means it involves both speed and direction. Since anything in orbit is changing direction at a relatively constant rate, it is constantly accelerating, but not necessarily gaining any speed.
They are constantly accelerating, but the acceleration is perpendicular to their velocity. For this reason their acceleration changes the direction of the velocity, but not its magnitude.
Also, add onto this that the equator is also where the centrifugal force due to the Earth's rotation is also at the greatest. So, on Mt. Chimborazo, the combination of maximum centrifugal force (pushing outward), and minimum gravitational force would allow someone to jump the highest I suppose. Before anyone starts spamming my inbox with "centrifugal force" doesn't exist, I am well aware that centrifugal force is not a real force, but the result of inertia. It is defined that way, so I'm fine.
@felrece. The only thing that the rotation of the Earth has to do with orbits is the fact that most satellites orbit in the same direction as the Earth. The reason for this is not because the Earth's rotation has anything to do with how an object orbits, but the fact that satellites launched in the direction of rotation require less fuel to reach orbital velocity.
Once we leave earth's gravitational pull, there is actually not that much gravity left to deal with. The difficulty is the distance, and the time needed to get their and back.
Your videos get better with every one. Thanks for this great information. :-)
You are on a bus traveling at a constant velocity. (velocity doesn't matter for the sake of this experiment)
You jump straight up and are in the air for exactly one second.
The moment you jump, the driver applies the brakes resulting in a constant acceleration of -10 m/s^2 (using negative to denote acceleration in the opposite direction of the velocity vector)
You would land 10 meters toward the front of the bus from where you jumped.
This experiment ignores air resistance and pixie dust.
one of the best way to know the answer is to remember the old training they had. the astronauts were put in a plane and then they would just make the plane dive, making them *float* in the plane
Wah animations!!! Productions value +5. Loved it before, love it now. Keep up the great work!
That depends on what you define as a 'science article'. Articles in scientific journals (written by scientists) don't talk about "zero gravity", because from a physics perspective it's a nonsensical term. Science articles in newspapers and popular science magazines (written by journalists) do use that term, because it's a term their audience will recognise, whereas the correct term; 'freefall' is associated with people jumping from airplanes (who are not in freefall because of air resistance).