Added: 4 months ago
From: destinws2
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  • omg ur so smart u pointed at the clutch

  • Newton's Third Law. As the wheel spins faster, it tilts the bike's nose up because the rotation of the wheel increasing the air pressure on top of the wheel, forcing the back wheel down. When applying the brakes, the wheel is still and generates air pressure on the bottom of the wheel to tilt the nose down. Off of the top of my head ( I am a sophomore in highschool, 11th year).

  • torque!!! the motor generated torque in the opposite direction, thus causing it to rotate the other way.

  • Jus to be a smart ass but didnt you point at the clutch when u said brakes :)

  • cool video man I think I learned a lot.

  • smart rednecks

  • whats the outro song?!?!?!?!

    awesome vid btw #ThumbsUp

  • as an mx rider i love this vid :D

  • backbrake on the bike is near the right foot:P 1:25

  • hey man your videos are awesome! mabie sometime you could one of my beats on your video?? :) btw i always thought Dirtbikers just shifted their weight to move the bike in the air. its pretty nuts

  • Nice vid. And the rear tire comes back down because giving throttle accelerates the tire pulling all the energy back.

  • The reason the bike pitches back up when you hit the throttle is just the opposite of when you tap the break. You have potential energy built up while it's sitting there, so once you hit the throttle, the wheel will transfer energy throughout and tilt it back.

    Greeting from Double Springs, Alabama!

  • @ringer454 to make it simpler the wheel needs something to push off of and the bike is the pivot and wheel uses the pivot and the energy from the wheel is great enough to spin the wheel at the max rpm and then extra rotation and energy to spin the bike

  • @zachawesomepudding Basically, yeah..

  • We all had to learn it hahah

  • I really like your videos! this one was nerdy, fun, and BADASS! Thanks, keep up the good work Destin :)

  • 0:27 LOL I LOVE THIS

  • Y is sipes riding that pile y not his factory bike

  • When you pointed at the "brake" on the handle bars that was actually the clutch, just to let you know.

  • i thought of the rear tire as a vertical frisbee.... if the frisbee is already in motion and you were to slow down only the rotation it would fall... hence "pushing" a frisbee leads to disappointment.... but if it were already in motion and you accelerated the rotation only... you'd also prolong its flight... does that make sense?????

  • learned something interesting thanks!

  • thank you for that

  • I just got an A on my physics project doing an analysis of the physics of motocross! I showed three aspects projectile motion, effective turning, and...... rotational energy! I showed your video to my class and you have some more fans coming your way. Everyone is impressed on how simple you explained rotational energy as well as your sense of humor! I enjoy all of your videos man, keep it up!

  • @kickingpaper

    Well done! I'm glad you were able to get aout a pencil and paper and make the math happen! Good job man.

  • Please do more Motocross videos! Like whipping and such things :)

  • @NikeGuy709 What a stupid question, lol.

  • Awesome, great help!

  • @NikeGuy709

    Engines can be loud. I do "loud stuff" almost every day, and I want to be able to hear when I'm 50. It's just smart to wear hearing protection when around anything over 80 dB.

  • @destinws2 I'm a hearing instrument specialist. I'm so glad to see you say that! You're doing your future self a huge favour!

  • The torque of the motor causes the front to roll back. Its an equal reaction to the force from the engine being applied to the weight of the wheel.

  • @NikeGuy709 Engines are loud. I work with loud things every day, and I want to hear when I'm 50!

  • @NikeGuy709 Cuz there coomfy. Why do you think?

  • I decided to do the physics of the back brake tap for my physics final this semester before I saw this video. I'm really happy I did find this video because of the given equation because I had no idea where to start with one. I figured that it pitches the bike down due to kinetic energy but that was the extent of what I knew. I race amateur motocross so it was really cool to see someone with the knowledge apply the actual physics. Awesome work and thanks a lot.

  • some of this stuff i already knew...but never seen in action...nor did i know the equations, not that it does me a lot of good...anything above pre-algebra was too confusing >.<

  • I learned quite a bit about motocross today but it would still scare the crap out of me to try something like that.

  • @Nodsinator I race motocross once you get used to it even mini races are backyard fun, Not pro races i mean

  • it pitches you back when you hammer the throttle because of the inertial momentum

  • I LOVE thinking about the physics behind these everyday activities!

  • My guess for the counter-spin would be that once the bike is in the air, it behaves as an isolated and or conservative system? Oh I just suck at physics. Cool videos, keep em coming.

  • Haha, Destin. "Ri.. uh-wait... what??"

  • did he clutch in when he tapped the brakes?

  • @ps3gamer2441 nope

  • @ps3gamer2441 Yeah. If he didn't the back tire would lock up and cause the engine to stall anddd prob eat shit on the landing.

  • I wonder, is the energy great enough for this to work with regular bikes? Not motor powered?

  • @PMoneyMillion it is :)

  • The equations mean nothing if you don't explain what the variables mean!

  • @georgepowell

    Engage your brain and seek out the answers.

  • @georgepowell lol dont try to be the smart guy haha

  • fascinating, I never thought about the wheels' rotational energy being changed mid air via brake and throttle Freaking Cool thanks for posting this.

  • love ryan sipes!!! awesome christian dude. but trey canards my favorite. sipes is second haha. its cool that you got to work with him. sipes had an awesome segment on "moto 3 the movie". i'm a huge motocrosser myself so thanks for uploading this! its awesome!

  • same reason it tilts foward just in the opisit direction

  • i now KNOW the use of sin and cosin thankyou

    you made school alittle more interesting cuse i relate your videos to stuff iv learnt.

  • lol Pro nerd, i love it :)

  • The torque of the engine rocks the bike back when the throttle is opened mid-air.

  • When he revs it up the bike pitches up because of opposite and equal reaction (newton's thrid law). Normally the ground and friction would be there to keep the bike level, but in the air (without friction) the opposite force of the wheel spinning goes through the whole frame and pitches the bike down. Something like that I think. (I'm a Communications major that can appreciate science. Rock on.)

  • I just love your vids and it was great to see you on the slingshot channel

  • i had nooo clue that the back wheel spinning/not spinning made a difference in the balance until now

  • just a guess: but I think it whips back when he revs because it creates a counter torque around the center of gravity, the opposite direct he is rotating. Just a guess.

  • cool

    

  • I wish I had found this channel last year, maybe I would have passed science by more than just the skin of my teeth

  • What if you're leaning forward too much?

  • @bemdav The result will be faceplant and crushed testicles :)

  • @PorscheLover87 That makes sense but is there any way to get your bike back?

  • Comment removed

  • @bemdav Oh sorry, forget what I've just said, I got it the other way, if you're leaning forward too much increase the throttle to level the bike.

  • lol I wish I had this video when I was in my Physics class

  • I learned something today, thanks.

  • Hey Destin, Thanks for making physics awesome haha... I absolutely hated it for the last 2 semesters of college because it was so dry and dull (it was for general education credits). Plus it doesn't help that I am a microbiologist haha. Love the videos keep them coming!

  • Reminds me of one of those crappy 4th grade Science Videos that always seems to make everybody laugh rather than learn anything.

  • well the technical term is mmsshhh

  • I watch your videos, then I tell my highschool Physics teacher abotu all it, and he hates me because half the time your right. lol

  • nice video again :)

  • 2:00 'oh wait what?' - classic

  • MOTOCROSS YEWW

  • Love it. I hadn't ever thought much about this, but it makes perfect sense. Also it works in the real world, and it's the application that matters more than the theory.

  • Dirt bikes look even more badass in slo-motion.

  • gyroscope effect

    

  • Google search 'Hyperphysics' first result. If the link dont work.

  • This brings me back to Physics 1 days. Newtonian Mechanics. I don't remember the common moments of Inertia(I) for different shapes. But for a hoop (wheel) with its rotational axis through the center perpendicular to rotation is:

    I=MR^2 ... mass * radius^2

    For linear to Rotational motion check out this nice page...

    hyperphysics.phy-astr.gsu.edu/­hbase/hframe.html

  • I wonder if the company "Iomega" gets their name from that formula, since their products rely on high-speed rotation to function. :)

  • Can you please answer the homework question in your next vid? :-)

  • You really need to set the white balance correctly on the high speed camera. This is wya to green.

  • i bet at the end screen with the previous videos everyone just watches the water baloon one in the screen before doin anything else

  • dude do you like personally know ryan or did you get invited out simply because of your videos?

  • @Evolution2810

    Awesome friend of an awesome friend kind of thing.

  • LoL, you pointed to the clutch lever and called it the brake :-)

  • and this is how remote control rc gas cars do flips n such yes?

  • Destin, can you explain the physics behind the whip? I'm too much of a wimp to try it, but I'd still like to know :D

  • While the bike is in the air we can treat it as an isolated system (apart from gravity, which exerts no torque). When he revs the throttle, the bike puts angular momentum in the back wheel. In order to do this the bike itself has to receive the same angular momentum in the opposite direction, due to conservation of angular momentum, causing the bike to pitch backwards.

  • @Teeftlis I agree. It's conservation of angular momentum not energy. Mechanical energy is added by the engine which converts it from chemical energy, and lost as heat in the breakpads.

  • Finally someone that knows how to spell "motocross" lol

  • pitches back up because the wheel isnt turning. For every action (the wheel turning) there is an equal and opposite reaction (in this case, the bike rotating as well)

    Love your channel man.

  • I'm in the middle of taking an introductory physics class in college. this video is the first time i've ever been happy about that decision. very cool!

  • i love the sport of motocross, its my sport: i had to know this before i could start racing and freestyle

  • Works on cars too Destin... planes not so much. I wanna see you on the bike demonstrating though.

  • Love this channel!! As for why it pitches back up, I would say if the back wheel is allowed to spin faster than the inertia the bike is currently at, it will cause the nose to pitch up again....sounds good to me but probably wrong..lol.

  • Now we've had rotational energy can we get an angular momentum video using gyroscopes and an explanation of a tippe top!

  • You are so awesome. Why couldn't school have been like this? I just got a physics lesson AND learned how to land a freakin motocross bike in under 4 minutes!

  • hey! waddayaknow, getting smarter everyday!

  • I love this show

  • Oh, there's some serious love goin on with that like button. Dislike-button is going all red.

    Say, does the bike pitch up just because the rear wheel stopped? Though it's veryinteresting, I was never that good at physics.

  • My girlfriend and I love your science down here in Australia. Keep helping us get smarter every day Destin!

  • what is the name of the song playing in the end of the video

  • Loved the good humour between you guys. Great vid.

  • Thanks! Showed my kid this, he tried it on his bike and it works.

    He now has a greater appreciation of Physics and that learning is useful in real life.

  • I didn't say don't try this at home so imma go jump some shit

  • What are the meanings of each of the variables in that equation? Is it related to or equivalent to the equation for kinetic energy KE = 1/2mv^2. Maybe I'm just unsure because of the context (this was a very interesting video). I'll just assume that I'm allowed to ask very nerdy questions on this channel. Thanks! Glad I subbed!

  • @pyrea17

    It's kinetic energy for rotating objects

  • @destinws2 Thank you. I am now smarter!

  • @destinws2 destin are you mormon?? if you are that would explain alot..im mormon

  • @thepapermakery Agreed. I was thinking the same thing. Oh, and so am I. Haha

  • @thepapermakery What would it explain?

  • @Supermassively why he dosent cuss and make sex jokes or smoke or drink

  • @thepapermakery Those could simply be characteristics of someone who is intelligent... and he is intelligent.

  • @pyrea17 All the linear classical physics has its angular (or rotational) equivalent. For example, (1/2)*I*w^2 (w is omega) is the angular equivalent of (1/2)*m*v^2. I represents the 'moment of inertia' which is analogous to mass, it's the property of an object which "resists" angular acceleration (higher I means it's harder to get spinning) in the same way mass "resists" linear acceleration. w is angular velocity (equivalent of linear velocity). PM me if you would like to know more.

  • @pyrea17

    The kinetic energy of a moving object is E=1/2·m·v² the kinetic energy for a rotational oject is E=1/2·I·w² it's not the same.

    -The omega(w) is the rotation velocitiy of the object. [w=rad/s]

    -The I is for the moment of inertia, and depend how the mass is distributed in the object that is spining. [I=m⁴]

    @destinws2 As you see everybody is getting smarter everty day. :D

    (Excuse me for my english i'm catalan)

  • @xavifam Thank you! I believe I understand now. So it is similar, but used for rotation instead of motion in on direction. Thanks again!

  • meh not fmx, not interested

  • i didn't know that the momentum of the rear wheel was enough to change the rotation like that...

    

  • dude ur a genius

  • excellent!

  • Destin whats goin on? we were in the same chapter in my physics book when you started this angular momentum stuff but now your 4 chapters behind. You should be doing fluid flow and simple harmonic motion by now.

  • "whip some love on that like button" (:

  • Cool. I got lernd today.

  • I gotta agree with zack10164. You just seem like someone who loves life, who loves what he does, and who loves sharing it with others. You have that child-like enthusiasm and intrigue with the many amazing things on this earth, like many of your subscribers have, but lack the energy and time and resources to explore those things.

    Keep up the good work man, you're positive approach to life in general is inspiring.

  • i love your videos ! simple mix of the science behind mundane activities !

    Love it !!!

  • EXCITEBIKE!

    

  • Conservation of angular momentum, baby!

  • The rear brake is on the right foot lol xD

  • @TigerClaws12894

    I was concentrating on the "vertical inertia of the sprocket bearings"....lol

    You're absolutely right. I was trying too hard to recall the equations, film with one hand, and describe the physics with the other, so I wasn't thinking enogh about the bike in front of my face. Doing this stuff on the fly gets hard sometimes.  Please forgive me.

  • @TigerClaws12894 Ya, and he pointed at the clutch when he talked about hitting the break, not even the front break lol.

  • ok so your trying to stop the back wheel rotation and explain how to do so by pointing to the front brake. this video was a failure. sipes is awesome though.

  • I mean, we all had to learn it. AHAH!

  • omg i didnt ever though of that this amazing

  • God I love Motocross <3

  • better than going school

  • @mexikin14

    Be cool stay in school

  • @destinws2 barhahahaha, good come back.

  • @destinws2 Then once you graduate, become an awesome school teacher :D

    ...oh wait, schoolteachers don't get paid enough to support a family. NVM. :C

  • @destinws2 Best adice given on youtube!

  • @destinws2 School is for fools!

  • Cool!

  • @destinws2 Great informative video as always! I have a question though: Isn't because of the rider's weight (he bends towards the front wheel) that the bike pitches down ranther than the rotational energy?

    And if my thought is incorrect, can that be achieved? I mean, can the rider pitch down the bike without breaking the rear wheel, by using only his weight?

    Thank you for you the very cool videos and keep up the good work!!!

  • @gsiotas1 Him bending towards the front wheel would affect the rotation a bit, but only a tiny bit (by shifting the weight away from the center of rotation he's changing the I of the formula). If you look the slow motion part more carefully you'll see that he actually slides a bit backwards while rotating (perhaps so he doesn't rotate too much), while the forward rotation accelerates (at a more significant rate) just at the exact moment the wheel stops rotating. Definitely great video :)

  • awesome , I learn something new every time I watch your videos.

  • lucky! are you friends with ryan?

  • Didn't show up in my sub box again? What's up with that :(

  • i had a sub today in class, he looked just like you.

  • Snowboarding Physics!!!!!!!

  • Motocross and Physics how does life get any better

  • so simple, yet amazing

  • So, now how about a video explaining the physics of the tail-whip?! I think it's conservation of angular momentum (like a gyroscope) but I'm not sure.

  • Oh man, I love the slow-mo camera shots!

  • these are the physics that i do this year:D

    nice vid

  • thanks, the slo-mo guys!

  • i don't know why but all your videos are so happy and just awesome, its like, while we watch your videos we have absolutely nothing else in the world to worry about except learning about awesome stuff! love this channel!

  • @zack10164

    Thank you. That's quite a compliment. This one involved lots of people. Josh & Ben did a lot to make this one happen. And of course the Sipes Brothers...

  • you want to herpy derp to get derp that is what u heard don't explain it to m

  • 666 like :O

  • you're a great guy

  • cool

  • lol pro nerd...

  • I love you man!!!

  • i like how he pointed at the clutch when he said "tap the brakes"

  • Nice video!

  • Keep this up dude. I learn more from your channel and Vsauce than any of my college classes. Speaking of, I have to shower and go to Physics where I spend most of the class telling my teacher how he's wrong :)

  • So do the fancy outfits help with speed or jumping height? ;-)

  • Hey, you all weren't too far away from me! Kentucky love :)

    Great video!

  • I believe they also have to apply clutch before braking mid air or else the engine would stall and once you got on the ground, SLAM

  • Counter-rotation. Same reason a helicopter has a propeller on the tail to stop that from happening.

  • Best channel on youtube, Deserves more views.

    Keep it up Destin

  • similar to doing a wheelie on the ground but with way less resistance. instead of the resistance coming from friction between the tire and the ground, the resistance comes from the inertia in the back wheel while it is stopped (tendency of an object at rest to stay at rest) and that's what causes the bike to rock backwards on the axis at center of the wheel

  • "I mean, we all had to learn it..." love it!