SCIENCE CLASS #2- Does Farting Make You Weigh Less?
Mark Rober
This is a juicy one. 70% people get this one wrong. I stream science LIVE M-W-F 1pm PT.

  • Mark Rober
    Mark Rober

    I stream science LIVE M-W-F at 1pm PT. Thanks for being here!

    • Zachary Siegel
      Zachary Siegel

      Oof sorry, I didn't know you just asked so I replied.

    • me Me
      me Me

      @Zachary Siegel idk what u sed but sure. I know now cuz he talked about it in another live stream but thx anyway.

    • Zachary Siegel
      Zachary Siegel

      @me Me So did that help you?

    • Zachary Siegel
      Zachary Siegel

      np bro

    • Kellen Hinck
      Kellen Hinck

      what about atlantic

  • Pencilcase99

    Mark: And that's what's happening with the Diet Coke! -Holds up a piece of Styrofoam- Me: O-o ???

  • Savage Chances
    Savage Chances

    Mark rober is insane I love him so much!

  • Luka Ruso
    Luka Ruso

    I whis you are my teacher

  • Aric Zacari
    Aric Zacari


  • Kaivaly Daga
    Kaivaly Daga

    Why didn't the aluminium foil float back up when it sunk?

  • Adam -EpicGamer
    Adam -EpicGamer

    I wish he was my teacher cause he is very good at making it fun. You’re doing great 👍.

  • Dane Bustrum
    Dane Bustrum

    Your so cool


    he is possibly the coolest most fun teacher out their

  • OmioFenilski

    Answering the important questions I see

  • Eric Grabe
    Eric Grabe

    When he talks about the "tug of war"between forces, I feel its important to point out that on the way up the buoyancy force is winning but when floating at the top buoyancy and gravity are tied.

  • Annisa Farid
    Annisa Farid

    Didn't make it to be a highschool physics teacher... ...but then teach physics worldwide. Thanks to the internet.

  • Jess Vriesema
    Jess Vriesema

    College-level physics teacher here with a few thoughts: 1) a more standard definition of weight is mass times gravity. If you fart, you lose mass, and therefore you lose weight-full stop. Buoyancy is a secondary effect. I wouldn't lose weight by tying a helium balloon to me. The problem here is that scales measure a force applied to them, which may or may not be a person's full weight. What the scale measures is weight minus the buoyancy force. 2) Farts would be compressed and under pressure inside the human body - which is why they come out! Because of this, the gas's density is slightly greater than if it weren't inside a body and under pressure. This means that the buoyancy effect described isn't quite as big as if the gas were not under pressure. (This probably wouldn't be a big enough effect to make a difference, overall.) 3) Suppose you fart and you lose 100 mL == 100 cubic centimeters of gas that is less dense than the surrounding air. With a mass density of 1.06ish kg/m^3, that's about 1e-4 or 1/10000th of a kg, or 0.1 grams of gas, or 0.003 oz. So, it's a *very* small effect, whatever the effect may be. 4) In addition to losing gasses, you expel a small amount of smelly solids (eww!) when you fart due in part to sputtering. I don't know the mass of the solids ejected in an average fart, but if it's more than (airDensity-fartDensity)*fartVolume == (1.225 kg/m^3 - 1.1 kg/m^3) * (100 cm^3) == (0.125 kg/m^3) * (1/10000 m^3) == 1/80000 kg == 1/80 g == 0.00044 oz, then you lose more weight due to ejecting solids than you "gain" by buoyancy - according to Mark's argument (see my point #1 about that!).

  • Mahima Bhardwaj
    Mahima Bhardwaj

    He mark was my teacher, I'd choose to stick with science in uni.

  • MysticTerror394

    Why does cruise ships need a pool...... Just jump of the cruise

  • Finding Me
    Finding Me

    You're like a gen x Julius Sumner Miller

  • Animous Gameplay
    Animous Gameplay

    How to make something neutrally buoyant: Get camera Get any object Picture the object Since it is not moving the forces are the same and u have a neutrally buoyant object to water. Or just change the density of the water

  • comcastjohn

    I got boss!👍😎

  • Damian Amerman-Smith
    Damian Amerman-Smith

    I disagree. While yes, farting would lead to the force of gravity on you be felt a little more, that isn't the question. The question is how farting affects weight, or mass times the acceleration of gravity. This means that, as farting lowers your overall mass, farting makes your weight less.

  • 30 minute music
    30 minute music

    This is the only teacher who I isn’t boring

  • Jonnyk Snake
    Jonnyk Snake

    i like these science classes

  • Noah Cosijns
    Noah Cosijns

    That Titanic scene should've been in the real movie "Jack, why are you wearing a skirt?" "It's not a skirt, it's a kilt!"

  • Hpnerd

    0:05 does that say gay?

  • Si74l0rd

    I'd argue that the Hydrogen Sulphide, or the eggy, sulphurus smell that you sometimes get in farts, is heavier than air, the ones that feel like something trickled down your leg after farting. So as before when I initially contemplated the question, it will depend on the exact composition of your farts. There may be a net gain or a net loss, or they may cancel each other out. Apparently not all people produce methane in their compositional fart makeup, hence not all farts can be lit.

  • Christopher Morrison
    Christopher Morrison

    Then why am I not the skinniest person in the world


      Christopher Morrison ....

  • Rojan Moktan
    Rojan Moktan


  • Krampo

    Why is gravity the same at the North Pole and the equator? Shouldn’t it be less at the pole?

  • Ejaz Binhendi
    Ejaz Binhendi

    Joe Biden weighs less.


    I have a question-if we fart in space, lets say during a space walk, will we be propelled or will the gas just expand in the vacuum of space?

  • Sammi Kerbal
    Sammi Kerbal

    if you were a teacher in my school i would actually learn ;(

  • Law Dorherty
    Law Dorherty

    Real science is talking about how much material is ejected in each fart. Also there is heavier gases as well. How else do they linger FOR SO long. A classic rock band in the 90s made a song about lingering farts or men. Same thing OFC. Blueberries IIRC, JK (CRANBERRIES) I need more science and the weight of each fart.

  • random

    isnt this like 6 grade science

  • Ember Smith
    Ember Smith

    One time we (my class) did a float or sink thing

  • Lord Twigo
    Lord Twigo

    You better teach my high school class

  • Ali Razi
    Ali Razi

    Im still not convinced if you fart your mass decreases so your weight decreases so you "weigh less" , but on a scale ,because your buoyancy is less, you appear to have a higher weight but you don't, you just have less buoyancy

  • hermit's fan
    hermit's fan

    What happens when its the same density as water??

  • Tami Robinson
    Tami Robinson

    You were right!!! That balloon and tennis ball comparison was amazing and easy to understand. Thank you for all your videos. They are so fun and educational. And mostly fun. And sadly I got the answer wrong.

  • kangaxx

    False, even ballons have weigh

  • Michael Stevens Jr
    Michael Stevens Jr

    Sadly I wasn't here when it was streamed, but i got the aluminum thing right in my head :). You're the best mark :)

  • InfinitePros

    Professor: I'm better!! Teacher: NO I AM! *"Amateurs"* "What was that, punk?" Mark Rober: *Amateurs*

    • InfinitePros

      lol im funny #

  • Erica D.
    Erica D.

    Can he be my physics teacher? He's better at teaching than most of my teachers 🥺

  • Isracalis

    Increase the surface area

  • Thomas Atkinson
    Thomas Atkinson

    I would have just got a super sensitive scale, get a big fart ready, stand on it and fart, then measure the difference. 🤷‍♂️😂

  • the Emerald Minecraft M
    the Emerald Minecraft M

    So, the question is: Does farting make you weigh less? Well, lets start by talking about why stuff float!

  • Kamalu426

    I bet that 25 pound weight won’t float

  • Pranav Suresh
    Pranav Suresh

    make a boat wid the metal

  • Eugenio Garza
    Eugenio Garza

    Man, I found this channel a bit too late, your classes are over!! **sad** So, to answer the question, there are several variables in play. What if you are in a vacuum chamber? farting will make you weigh less!!! You forgot to take into account one variable: external density. if you are inside a blimp, full of helium (or hydrogen), farting will make you lighter.

  • Bryan Martinez
    Bryan Martinez


  • BlAzE_savage

    Did this grown man play with dolls I think he did

  • loodhoodin 1274
    loodhoodin 1274

    Nothing will quench my thirst for silly knowledge

    • SlimeB4


  • Sushi Cream Puff
    Sushi Cream Puff

    *farting makes you weigh more* Goddamit, this is why i'm fat

  • Mirza Arnaut
    Mirza Arnaut

    Can't watch it because of those interlacing artifacts ... xD

  • william Browne
    william Browne

    More space

    • william Browne
      william Browne

      It also works when u want to stay below water and don’t store any breath

    • william Browne
      william Browne

      For the tennis ball secret is if it is The exact density of the water if u pushe it down at a certain place it stays there

    • william Browne
      william Browne

      Yes got it right

  • Ray Ieen
    Ray Ieen

    it took 4 milliseconds to figure it out

  • Mathie Family Channel
    Mathie Family Channel

    spread out the metal evenly!

  • Jacob Romo vlogs
    Jacob Romo vlogs


  • Gregory McDaniel
    Gregory McDaniel

    A light bowling ball would of been a good example

  • Sebastian Rivero Lozano
    Sebastian Rivero Lozano

    How much do farts weigh?

  • Asriel Dreemurr
    Asriel Dreemurr

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    Asriel Dreemurr

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    Asriel Dreemurr


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  • Allassea1980

    Mark you are going to be an amazing teacher! If you had taught me when I was younger I'm sure I would've passed my science class. Don't doubt yourself. You are going to rock at it and I've got a feeling that you are going to change someone's life in the process. I won't be around to hear about it, but just keep it in mind. One of your ex students will let you know what difference you made to their life in the future.

  • LoosSerine

    Well if I had Mark for physics, I'd have certainly done a lot better.

  • Craig Merlin
    Craig Merlin

    But what pressure are farts kept at within the body and how much volume change is associated with that pressure.

  • Ted Danville
    Ted Danville

    The reason a lot of people got the wrong answer was because they’re confused between weight and MASS. Yes, if you fart, your mass will go down. But weight and mass, while in most cases act the same way, are actually different things. Weight is just the force of the ground pushing up into you, so if you go to the moon, your mass will be the same, but you’ll weight less cuz there’s less G on the moon, meaning the moon only push you back at a smaller force. While mass represent how hard it is to move you, so if you have an extra pocket of fart in your body, that’s gonna take extra effort to move you.

  • Thinking Like A Human
    Thinking Like A Human

    just because you're less dense, it doesn't mean you're heavier?

  • Rabiaa444

    I wish these videos where in my native language.. i understand a lot in English but math and physics is hard in my native language let alone in an another language...