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

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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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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

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

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

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

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

onegaimatte
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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 :)

rolexshadow
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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!

lydia_playz
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Very good explanation love it I understood everything 😊

theanimalkingdom_eak
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Awesome video.Perfect real life example.

experiencebg
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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

rhoadess
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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!!!

TheYounes
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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.

mecampbell
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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

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

NJJt
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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.

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

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

bumpriderolling
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Dude yousain bolt that's how u prenounce it

ALGN
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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.

LachFlex
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It's actually pronounced "Yoosain"

arissa