Finding average speed or rate | Ratios, proportions, units, and rates | Pre-Algebra

Finding average speed or rate | Ratios, proportions, units, and rates | Pre-Algebra | Khan Academy

Рет қаралды 388,494

12 жыл бұрын

Using the formula for finding distance we can determine Usian Bolt's average speed, or rate, when he broke the world record in 2009 in the 100m. Watch.
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Пікірлер: 144

@Xonar_ 2 жыл бұрын

best part about khan academy is that he repeats his words several times and teaches us slowly unlike some math teachers who get finished when you look another way for 5 seconds

@tofuteh2348 7 жыл бұрын

Khan's aim is not to do crash course lessons. He wants you to 110% fully understand what he's teaching.

@tofuteh2348 2 жыл бұрын

@JOSIAH MUTUKU yes

@TheEightBitLink 12 жыл бұрын

Usain Bolt, fastest human ever: 23.3 MPH Average Housecat: 30 MPH The more you know

@scringles773 2 жыл бұрын

U dare underestimate the cameraman?

@jennyshmit6172 4 жыл бұрын

You sound like my substitute teacher.. mom I'm scared.. he's fallowing me again..

@onegaimatte1845 3 жыл бұрын

Your voice is so soothing, I slept on my laptop.

@rolexshadow 12 жыл бұрын

i have been watching your videos (chemistry n biology) for a while n it helped me a whole lot. n i think its nice of you to do a vid like this but wat i really like is that u used the fastest man alive which is from jamaica n im from jamaca :)

@lydia_playz1792 6 жыл бұрын

I recommend mathanyics if you do not like this. Please like, if you try mathantics and you think mathantics is great, try to get this to the top so anybody who watches this can check it out!

@TheYounes909 12 жыл бұрын

THUMBS UP!!! Khan should make a vid about what the speed of bolt would be if he were not to chill the last piece of distance THUMBS UP!!!

@rhoadess 12 жыл бұрын

average speed was 23.35 mph. If we assume his acceleration was constant, then a=2.179 m/s^2, and that give us a finial speed of about 46.7 mph

@experiencebg 12 жыл бұрын

Awesome video.Perfect real life example.

@theanimalkingdom_eak9685 6 жыл бұрын

Very good explanation love it I understood everything 😊

@SamPand 6 жыл бұрын

thx this vid rlly helped me

@mecampbell30 12 жыл бұрын

My guess is that a charging elephant's average speed would be much slower than a human's over 100m from a standstill. ;) Great work, as always, Sal.

@luffy2114 12 жыл бұрын

Thank you for telling

@Zythrst 12 жыл бұрын

I love how the German tv has this wrong on the screen.

@jsymons1985 12 жыл бұрын

The fastest human footspeed on record is 44.72 km/h (27.79 mph), seen during a 100 metres sprint (average speed between the 60th and the 80th meter) by Usain Bolt

@N0JJt 12 жыл бұрын

@VanMedia The reason your velocity increases is if your acceleration is constant.

@bru5142 6 жыл бұрын

Thx

@obelie1401 4 жыл бұрын

Thanks for telling me

@jayex 12 жыл бұрын

you're not considering the fact it would have taken him 20 meters at least to reach full speed. You should have times 50-80m to get an idea of how fast he runs.

@SSCExcitairHP 12 жыл бұрын

Sure let's do it

@bumpriderolling9158 6 жыл бұрын

He does well, but I sure wish he had a white board. Thanks

@ALGN28 10 жыл бұрын

Dude yousain bolt that's how u prenounce it

@XtraFilm-zf8jq 6 жыл бұрын

jordan miller your wrong

@ahgoon69er 12 жыл бұрын

If someone tell you to do another similar question, can you do it? If you can't you should watch the whole video..

@ryan-ov3jg 3 жыл бұрын

commentator: [speaking german] nice captions

@priscanemger783 6 жыл бұрын

You are an awesome teacher, thank you! 👍 👍

@arissa6372 5 жыл бұрын

It's actually pronounced "Yoosain"

@Youssef-iu8dn 3 жыл бұрын

Usain

@LachFlex 12 жыл бұрын

Lol. My point is the average speed of Usain in this race includes the first second (and likely few seconds) of him being stationary, and then accelerating to top speed. Therefore taking an average you are going to have a lower speed than his speed as he passes the finish line (top speed). And didn't you know about that the quadrennial pachyderm games held in Botswana? - Where the top speed of an elephant (Barbar indeed) was clocked back in 1962.

@FroMaestro 12 жыл бұрын

should be "YOO-sain" Bolt lol

@incarnate1 12 жыл бұрын

That is including acceleration/deceleration, but between the beginning and end he reaches speeds of 28mph.

@FlyNavy906 12 жыл бұрын

Well if the person is trying to learn the math and understand it the 13 minutes isn't a waste at all.

@nooormann 12 жыл бұрын

Hey khana, how about the wind speed

@Patrickstaroundpants 12 жыл бұрын

This is awesome

@Ureyeuh 6 жыл бұрын

Does anyone know why you get a different answer if you don't convert from m to km before converting from seconds to hours?

@robertrobinson9789 5 жыл бұрын

Yes because 1m=1000mm but 6x1m=6m 6x1000mm=6000m. 6000mm=6m. They are the Same answer but you need to covert the units. (If this wasn’t what you were meaning please give a example

@goldensilverstar 12 жыл бұрын

looks like sal khan is obsessed with usain bolt and sprinting

@redfire154 12 жыл бұрын

You should blur out the average speed that displays on the TV clip at the end of the run. It says 37.6kph on screen @ 00:31 min

@SamPand 6 жыл бұрын

german video at the beginning 😂😂😂

@koirblx2503 3 жыл бұрын

oop-

@marrsbar5040 6 жыл бұрын

So rates are just a quicker form of finding an equivalent ratio?

@bareaahmalik238 6 жыл бұрын

I UNDERSTOOD!!:)

@farhanqadri 2 жыл бұрын

I hate how they are 360k views but only 800 likes and 110 dislikes :(

@suzannecortese8282 9 жыл бұрын

math man that's hard math

@zahaiddelgadillo6311 9 жыл бұрын

It was 27.6

@Sxthvr1 9 жыл бұрын

Beachkiller101 lol

@naoise09 3 жыл бұрын

can someone pls help with this Tom cycled 24 kilometres in 45 minutes. What was his average speed in kilometres per hour? i cant understand it and it is on the sample thing for the end of year STen test pls help

@VanillaDazzle 10 жыл бұрын

That's almost a marathon in an hour if he could keep that speed, which no one does. Even the Kenyans run it in 2 hours and change.

@PhrozenTiger 12 жыл бұрын

TV says 36.7 km/h Calculator says 36.44 km/h .. intresting.. ^^ ( I know, we rounded of to 10.4 before the end of the problem )

@slothlovechunk 12 жыл бұрын

I don't like how he compares average speed to instantaneous speed of a charging elephant at the end. :) They 'clocked' Usain at over 27mph in his 100m race.

@imhiLARRYous 12 жыл бұрын

Khan is calling Usain slow! inb4JamaicaRioters! xD

@YoNiQe 12 жыл бұрын

he said he wanted to see what his "average speed" was in the beginning of the video :)

@LaborHours 12 жыл бұрын

Didn't know elephants were that fast.

@jsymons1985 12 жыл бұрын

That is not his peak speed, however, it is his average rate

@rhoadess 12 жыл бұрын

How did you figure this out?

@Ashiq.Ibrahim 5 жыл бұрын

By Using his head

@gda295 5 жыл бұрын

8:30 in [about] says [sal] 1000x bigger . no, 100x bigger.

@boldblazervids 12 жыл бұрын

go Jamaica's Usain Bolt!

@cmh1236 8 жыл бұрын

I just watched a texas tech college football player grant run 26 mph in full pads

@phoenixocean8594 7 жыл бұрын

Nice lies

@jtrain8506 6 жыл бұрын

Yeah to e is on the Dolphins now lol he is vary fast!

@Unknown-cs7ws 3 жыл бұрын

I'm still hella confused;-;

@diazisbaby1916 3 жыл бұрын

O_o

@meowth900 12 жыл бұрын

Yay! German!

@lourdkymanemariquit3747 2 жыл бұрын

Wait the video was published 9 years ago

@maru-kq6ns 3 жыл бұрын

*he sounds like jschlatt*

@irawr4pie 12 жыл бұрын

coo

@LachFlex 12 жыл бұрын

I don't think the comparison to the elephant it that applicable; it's his average speed that you are comparing to an elephant's top speed. I think his top would have been over 40km/h

@IsaacMazur 12 жыл бұрын

isnt it just a little over ten m/s?

@710418oo 12 жыл бұрын

He runs at 37.578288 km/hour.

@jdablada 12 жыл бұрын

13:00 your numbers and significant figures are incorrect.

@GigaBoost 12 жыл бұрын

Distance/time, no?

@Bluecloudandrew 12 жыл бұрын

8st

@SSCExcitairHP 12 жыл бұрын

I bet you'd like that.

@berkhasiat 12 жыл бұрын

12 year olds should watch

@rhoadess 12 жыл бұрын

Okay, I think an approximate equation for velocity with respect to time would be something like v = 27 - 27/(x-1), assuming max speed is 27mph. I wonder if there is a better way to do this.

@calebburns2437 6 жыл бұрын

It's hard to focus with that huge picture in the middle of the screen

@mrnatehammy 12 жыл бұрын

ITS PRONOUNCED yu-sane-bolt

@TysonE 12 жыл бұрын

But how do we know who the fastest elephant is? Elephants don't attend a pachyderm games where they find the fastest elephant in the world (we'll call him Babar) and we are comparing Babar's fastest ever clocked time in the 100m sprint to Usain's average. The elephant's charging speed (25mph) is most likely the average.

@DerrenBrown100 12 жыл бұрын

Top speed is around 27.5 mph

@_alc.v 4 жыл бұрын

oOUuusain bolt

@rhoadess 12 жыл бұрын

sorry this is what I meant v(t) = 27-27/(t-1)

@Cammie010 12 жыл бұрын

not sure if trolling or...

@iguessitslexi7708 5 жыл бұрын

umm, I'm still confused. Help?

@mogmaboissad3018 5 жыл бұрын

Tell me the doubt,I will try to clear it

@spencerdeclercq3742 5 жыл бұрын

ooosain bolt

@MelkorHimself 12 жыл бұрын

100m/9.58s = 10.44m/s or 23.35 mph (37.57 km/hr) I just saved you all 13 minutes.

@ColeEclipse 2 жыл бұрын

Thx. I still watched the vid, but thx

@ezEricZhang 12 жыл бұрын

Wasn't it 2008?

@lydia_playz1792 6 жыл бұрын

I mean mathantics

@christian-vg1wc 7 жыл бұрын

lol he had a csgo crosshair to write with

@fiire_stormm7279 5 жыл бұрын

Christian P. Ikr

@leopve 12 жыл бұрын

6th

@thecatsnailthing2332 4 жыл бұрын

Im still super confused

@qre8ivity 12 жыл бұрын

10.4 m/s is his average speed

@dejaaf3259 3 жыл бұрын

Ouuu sain bolt 😭😭😭🤣

@LelanieMirambel 2 жыл бұрын

how do we solved this: Supposed the speed of the car had been noted during this time and is modeled by the quadratic equation y = 3x^2 + 17x - 20, where y represents the speed of the car in k,/hr, and x represents the number of minutes after you started following the car. How long did it take for the car to be under surveillance before it could finally stop on the side of the road? Did the driver of the car really break the speed limit of 100 km/hr?

@SSCExcitairHP 12 жыл бұрын

geez? isn't it jeez?

@willagem28 12 жыл бұрын

you really don't need to say intuitive all the time

@lydia_playz1792 6 жыл бұрын

I would have a name from the lord of the rings but I am a girl!🤣🤣

@quasia9921 5 жыл бұрын

Okki first of all it is U(you)sane not ousaine

@nicholas11121 12 жыл бұрын

No he hasn't done LAW yet

@Fungasaur 12 жыл бұрын

Clearly, but he has to make the videos for a broad audience. He can't just assume that everyone knows basic mechanics.

@flexmasterjj 12 жыл бұрын

The man's name is pronounced uuu-Sain not ooooo-sain

@HoneyIEducatedTheWeb 12 жыл бұрын

lol of course he gets tired. He just runs faster while he's tired.

@wtfyman 12 жыл бұрын

hmmmmm, I want to know his maximum speed....

@elmerdiaz2359 10 жыл бұрын

23 miles for all the lazy ppl who did not want to watch :3

@arissa6372 5 жыл бұрын

We don't wanna just know the answer, the whole point you would click on this video is to know how to do it.

@supdenfoosukka 12 жыл бұрын

*AVERAGE RATE*

@Myrslokstok 12 жыл бұрын

But the reaction time was like 0.14 seconds so the speed is a bit faster. But nice video any way.

@nathanlolo99 12 жыл бұрын

lol his 200m record is only 3 hundredths of a second off of double his 100m record

@noreaction1 12 жыл бұрын

@pureexpose it doesn't make you any better to talk down to people like that

@CodOilBeer 12 жыл бұрын

whatchu doin here jayex23?