Measure height with a watch! Cliff jump science

Birt 5 ágú 2014
This is a simple trick using high school physics where you can measure the height of really tall objects like a cliff, using just a stopwatch.
Special thanks to Active Life Store for the GoPro shots. You can get one from them here:
Here is a link to the FREE app (free as in FREE, as in I don't even have any ads in it or make any money off of it whatsoever) in the app store (sorry, no android at this time):

I make videos like this once a month all year long while supplies last:
FACEBOOK ME: MarkRoberISchats

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  • hi

  • The best part is u can even release it with a horizontal velocity

  • “it’s that simple” me still trying to read the title

  • What about the time lag due to speed of sound reaching your ear

  • 11th class science

  • correct me if im wrong but cant you get a close estimate on smaller objects by just multiplying the time you get from leaving the top and hitting the water by 9.8?

  • hi im 7 i i love science i cant do math like that

  • Mark: All you have do is grab your phone and jump into the water Me: *Wait a minute...*

  • I just hang my Jimmie off the cliff and if it reaches the water it is 32 feet. That water is cold, yeah, and deep too.

  • Other ways to find the height of the cliff with a watch, "I'll give you this nice watch if you can tell me how high the cliff is"

  • Ok, but what did you really say, where the v.o.'d "compact" was?

  • I love the tree height measurement with rock. It's great.

  • Cool thing is that guy went to moon to give the proof that all objects fall at same rate irrespective of mass.

  • But the uncertainty in you reaction time on the stopwatch will be about 1/4 second.

  • one of my favorite space videos of all time. "How 'bout that!"

  • I hat if for example you chuck something down a hole and measure it based on sound but because of the large distance it becomes inaccurate as sound can only travel so fast

  • It just doesn't make sense to me that a freight train engine car would fall from a cliff as slow as my body would. I am not saying that's incorrect. It is just hard for me to believe.

  • OMG I somehow thought you can measure the height of the person by measuring the dropping time

  • how would you measure the height of a helicopter jump

  • Can i use this method to measure the empire state building?

  • what is the equation for meters?

  • How funny I just got done learning about this and simular things in science ( and I'm in 6th grade am I supposed to know how to calculate newtons and acceleration due to gravity and how to measure somthig based on how long it took to fall)

  • Hmmmmmm. Physics tells me that at scout camp when I was 11, I jumped about 144 feet... 16(3)^2 following PEMDAS = 16(9) = 144 I question this.

    • Given that gravity probably hasn't changed a lot since you were 11, I'd take a closer look at the "3" ...

  • yeah using science to count in imperial units .. *facepalm* this guy worked at N.A.S.A he should know better :( but its old video ... with metric system you actually know how physics works, that you have some kind of gravity that accelerates (9.8 m/s) and use "h = 1/2*g*t*t" you and thinking about you falling and accelerating down you can discover new things like you have to start accelerating in first place (you are not instantly getting 9.8 m/s) and about air resistance and drag and you can start count it more precisely and also you are not falling strait down when you jump from cliff you have side motion or if you have initial up or down motion since that will affect the time of drop.. but when i see 16*(x*x) i get nothing in mind :( i don't even know how big foot is .. in metric its easy

  • It would be inaccurate as we have to take air resistance also

  • I think the pictre for the vid is a bit inappropriate...

  • me watching this at the end of 2020 8:22

  • back when mark used clickbate

  • What is the equation but for the metric system?

  • with the equation, why do you times it by 16?

  • In india , you have these questions on exam papers

  • At no point was I expecting to see an astronaut holding a hammer and a feather going "Watch THIS."

  • i don't even need to watch this video, I already know its 1/2(9.81)(time)^2 from the title, but I also know that mark probably explained everything in here what took my school a total of 5 hours to teach.

  • Me and my brother HATE math And for some reason we’re good at it

  • “How ‘bout that”

  • Who’s watching this is 2020

  • Who got click bated with the bikini lol

  • How to get bowling ball out of water?

  • how old are you mark

  • *How does a scale measure the weight of different objects, if all objects are attracted by gravity equally?*

  • Instructions unclear! Friends did not enjoy being pushed of buildings to figure out the height!

  • We know that heavier items fall faster due to their own gravity. Granted, it is such a small change, we don't use the measurement in most engineering calculations.

  • So that was what Pipin was doing...

  • "dad, how tall is that building?" "lets find out." pulls out cliff timer "head on up there, son."

  • yong

  • Hey Mark, You dropped this | \/ 👑and🧪 please don’t tell me it’s acid

  • Your app is fucked up

  • *Science only goes so far, then comes God*

  • 0:20 - Been stuck for minutes trying to figure out where the 16 came from. Turns out it's because he was using freedoms per bald eagle squared.

  • For all my metric fans out there, if you want to know the height in meters instead of feet, simply use d=4.9(t)^2 .You're welcome!

  • Smb3

  • “How bout that.”

  • Thanks for the apo

  • I tried that when measuring the height of trees in a survey, sadly it took so long to complete it, because i was hospitalized for several weeks after each jump!

  • He does cuss when properly agitated!

  • what happens if you use different force on the objects that fall?

  • 2:05 Thanks for including Tanooki Mario! Doesn't seem like the other 2 objects though. Mario logic.

  • hey Mark, if you see this comment, can you put your app on Play Store please? (if you ask, I love doing video archeology sometime)

  • Wait the weight?????

  • coooooooooooooooooool

  • Ruining ISchatsrs' lives since 2013

  • The only guy verifying cliff jumps

  • 2014 nah2015 nah 2016 nah 2017 nah 2018 nah 2019 nah 2020 yes he waited enough

  • "How 'bout that!" -man of science in an extremely deadly enviornment.

  • 2:54 Nice

  • True fact: you have no idea what he is saying half the time Also true: you click on his videos anyway

  • start using metric system first.....

  • nice voice over XDXDXD

  • 3:35 Mark Rober sounded like he swore

  • you're the greatest nobody can defeat you

  • Hi

  • Stop using cheap clickbaits and ancient units of measurement (or at least provide both), and I will subscribe to your channel again.

    • that'll scare him. whatever will he do without you.

  • 0:01 you are welcome

  • 0:30 took not taked cmon rober

  • My iPad didn’t like this audio 2:07

  • I was thinking, "OK, 9.81 m/s^2 acceleration" and then you said "16" and I immediately was disappointed in you for not teaching your ISchats fans to use standard SI measurements :)

  • Only if I knew this when I went caving, then I would know how deep the endless pit is

  • Downloaded the app strait away


  • Bro on Christmas my wish is that I can be smart as him I wishhhhhhhhhhhhh

    • Work for it. It isnt as much as how naturally talented you, its how much effort you put into your education. And its not a tell myself and I am, you have to put in the boring hours of learning if you want to succeed

  • What is 48ft in an actual measurement?

  • Who watching this in 2020

  • He sounded so different

  • 1:58 "how bout that" 😂😂😂

  • I LOVE you Mark

  • But... But this video wasn't planned 8 months ago 🤦🏻‍♂️

  • americans am i right

  • Nice learned something new today.👍

  • Me and my friend judged that the Empire State Building is 381 m tall. Rest In Peace terry

  • The air resistance was not taken into account.

    • Yes it is not 100 percent accurate. He acknowledge this

  • me telling my friends i like to watch Mark Robers Videos They saying hes a nerd me saying that i dont care if hes a nerd (hes not) i just think its cool that hes so frickin smart.

    • Being smart is an effort. Mark Rober has a ton of effort and passion in what he does

  • The apps told me that planes are in the space :O

  • the time in youtube vidios are diffrent in real life

  • But it depends on if they jump,fall or get accidentally-on purpose pushed off the cliff

    • Biaka For ... science

    • Why would you time someone who falls or accidentally on purpose pushed off the cliff, just to know the height.

  • when you used imperial rather than metric, that hurt. nasa themselves lost a $125 million mars orbiter because they measured everything in imperial units but everyone else used metric. the us needs to convert to metric imo, it’s so much easier to understand

  • How did I learn this in like 7 seconds (Nobody thought me this till now)

  • I’m only six years late

  • Lol 61’ wawawawawaaaaahhhh

  • Now this is a new way to discover how high my skyscraper is.

  • ew feet