[Youtube Review][Mark Rober] Measure height with a watch! Cliff jump science

(Recommended)Popular Videos : [Mark Rober] Measure height with a watch! Cliff jump science

 

This time, I will review the popular YouTube videos.

These days, even if it's good to watch on YouTube, sometimes people skip it or don't watch it if it's too long.

When you watch Youtube, do you scroll and read the comments first?

To save your busy time, why don't you check out the fun contents, summary, and empathy comments of popular YouTube videos first and watch YouTube?

(Recommended)Popular Videos : [Mark Rober] Measure height with a watch! Cliff jump science

https://www.youtube.com/watch?v=z68vta3N5kg

 

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Summary Comments : [Mark Rober] Measure height with a watch! Cliff jump science

Sa**********:

I'm not usually this guy, but I was curious so there you go
gravity= 9.81
1/2 ( gravity x (time)^2)
1/2 ( 9.81 x (time)^2)
or in a simpler way... ( 9.81)/2= 4.9
4.9 x (time)^2
so just square the sample of time and multiply it by 4.9

here's a potato...O
thank me later!!!

45************:

We can come up with an even more accurate measurement If we consider taking speed of sound into account,
Since we are using sound to judge the height, we have to consider the time to taken for the sound to reach Mark's ears.
Speed of sound( Approx.): 343 m/s
Converting meters to feet: 1097.6 ft/s
Time recorded: 1.71 s
Height of the cliff: 46.7 ft
So now, The sound of the rock hitting the water has to travel all the way back to Mark's ears before he stops the timer.
Time taken by the sound to reach Mark: 46.7 / 1097.6 = 0.04 s,
Sound takes 13 ms to reach the top....
The time taken by the rock only to hit the surface of water: 1.71 - 0.04 s= 1.67 s
Now, Calculating the height of the cliff: 44.62 ft
This justifies the reason why Mark finds the height to differ within 2 units.

Ki******:

for a moment there I was cracking my head on how did you come up with 16....gravity is only 9.81m/s2.....then it hit me....feet....imperial....Ahhhhhhh....my brain!

Is***********:

For metric people, then 4.903*t^2 is good, and for feet, then it's 16.1*t^2. Yes,I used integration.Also for feet isn't it easier to do (4t)^2.

K*:

Um... correct my math here... but if V naut is assumed to be 0 as he is starting from rest and jumping off, and a=g=9.8 m/s^2, then the equation simplifies to d = (9.8/2)(t^2)... and 9.8/2 does not equal 16...

Now I'm not trying to be a dick... but am I wrong? If so, please explain

 

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Playtime Comments : [Mark Rober] Measure height with a watch! Cliff jump science

Ch*************:

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.

Is***:

what happened at 2:05
"for most solid compact objects"

Lu**********:

2:43 But there is a time delay (speed of sound) that you have to take into account. And you can only calculate that if you measure the time between impact and hearing. So you inevitably have to see the object and if you can do that anyway we can use the speed of sound to calculate the distance.

On************:

1:58 "how bout that"

Mi************:

2:07 There’s been a glitch in the Matrix

wi******:

1:46 I dont know why this is so funny for me

y3**********:

0:00 so today we’re ayrere cliff jumping

Ni****:

1:49 is that master chief?

En************:

2:05 I don´t think that an Italian plumber with a raccoonsuit can slowly fall...


but that's Nintendo logic XD

He*****:

2:05 - love your games references. I particularly love that Mario 3 power.

 

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Top Comments : [Mark Rober] Measure height with a watch! Cliff jump science

Si**********:

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!

br*********:

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

Ap********:

Why would you not do physics in metric units?

Ro************:

100 foot cliff jumps AREN'T? Well, you know how bad GUYS are at measuring LENGTH...《grin》

Da**:

why u no metric

VN**:

'self respecting man of science' - uses feet for distance

jo*********:

Honestly, I came here just to look at the girl.. and she only makes a brief appearance for like 1 second. Damnit man what's wrong with you?

fr**********:

"How bout that?" LOL

pl****:

Oh cool, I'm gonna measure the hight of this bridge now

Sp********:

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

dr*******:

If the hole in Siberia is sufficiently deep, the speed of sound delay from the splash will result in a significant overestimate. Just saying.

Ro*********:

Mark,
 Can you develop an app that can convince some people around here to start jumping off cliffs, without the water of course????

Ra*****:

Mr!. you worked in NASA and love physiscs.. PLZ! METRIC!

Sp***********:

But what if its a massive whole and it takes time for the sound to travel to your ear?

Na************:

If you want the equation for meters it's d=4.9t²

on**********:

More direct approach for a metric result: g=9.8m/s/s so you can get the height in metres by multiplying 4.9*t*t (rather than doing 32/2*(t*t)*.308).  Physics is phun.

Sc******:

feet? how many bananas is that?

Gr********:

IMPRACTICAL JOKERS JUMPED OFF THAT

GM********:

Just remember to account for speed of sound for bigger distances kids.

Sp******:

Who else is going to watch a gismoslips video now and use things equation

Br*********:

2:54 if its an 100 foot cliff jump then its 100 feet duh

fr********:

Those cliff jump guys are obviously only able to measure with one significant digit and therefore rounded up to 1x10^2

Je************:

I WISH U WERE MY SCIENCE TEACHER , life wpuld be fun and i would learn alot at the same time :|

ma***************:

great app, but the fact that people cannot do 16t^2 is just sad. 
also when you hit termial velocity doesnt this app stop working quickly for example if it takes you 200 seconds to fall from a plane this function tels you you fell 640,000ft or roughly 195,072 meters. or 195km. ie from space. although that takes significantly longer to fall from then 200 seconds. 
or if you take the time it took 
if you take a real life example, felix who jumped from 24miles up or 38.6km. it took him roughly 4 minutes or 240 seconds. this function says he fell from 280.904km 

Kn*********:

If you want meters just use 4.9(t^2). For longer falls (ignoring drag), if judge time by sound you have to account for the speed of sound which is approx. 340.29 m/s at sea level. You can get a more precise measurement quickly by dividing the initial distance approximation by 340.29 and then re-doing the estimate with the added time. At 1000 meters you will get a 26.3% more precise approximation of 854m using this method as opposed to 631m without anything. There is probably a better method but I can't think of it right now.

 

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[Mark Rober] We gathered comments about popular videos and looked at them in summary, including play time, and order of popularity.

It's a good video or channel, but if you're sad because it's too long, please leave a YouTube channel or video link and I'll post it on this blog.

 

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