Braking Distance - Explained

[@1992it]

rewatching this 10years later as a long term subscriber, you have changed up your style since this video, but points remain as clear as always.

[@EngineeringExplained]

Frictional coefficients can greatly exceed one when you consider how soft rubber sinks into the pavement, thus creating a barrier that either has to shear off (burnout) or move (acceleration).

[@jean-pierreagosto8803]

just had to say i just started a school for automotive technology, nd one of my first classes is to learn the basic info for all car systems and your videos have giving me an advantage in clas, as i listen to the teacher i remember things from ur videos, just want to say thanks and keep it up

[@EngineeringExplained]

I may eventually make a few more videos on braking. It's not as simple as dividing the mass with acceleration by the number of brakes, as the front brakes will carry more of the load since weight transfers to the front under braking.

[@EngineeringExplained]

Yes. Since we have the equation u=fN, f is the frictional coefficient. If it's less than (say .8) then it makes our maximum stopping G's 0.8g's, so it adjusts the stopping distance accordingly.

[@EngineeringExplained]

This is completely true. Grip goes well beyond what the eye can see. And wider tires will have more contact, allowing more rubber to mesh with the pavement. There is a flip side, however, as with the weight more spread out, the tire won't sink in as much. This is why the grip effects are as not drastic with wider tires rather than softer rubber, nonetheless it is something important to point out, thanks.

[@EngineeringExplained]

Not if your standard brakes can lock up. If your brakes can lock up, there is no greater force you can apply (with purpose). Now tweaking the ABS can yield improvements, if it cycles more times per second, keeping you closer to the edge of the frictional limit of the tires.

[@EngineeringExplained]

Hey, glad I can help, that's awesome. Good luck to you!

[@Roi93]

I really appreciate you effort and excellent work! Greetings from Portugal.

[@EngineeringExplained]

yes, I'm an ME. Thanks for watching!

[@EngineeringExplained]

To answer your question, yes, it attempts to keep the car at the peak static friction level.

[@oldfashionedwrx3574]

ABS stops in a shorter time because the coefficient of static friction is much larger than kinetic friction? is that right? also thanks for the video, I am watching all your videos, I appreciate the time and effort you put into them, I have learnt a lot and this are inspiring.

[@EngineeringExplained]

Eventually, probably. The first number is the viscosity of the oil when it's cold (when starting the engine). The second number is the viscosity when it's warmed up, the higher the number, the thicker.

[@dragospahontu]

This is an easy straight to the point vid. Well done.

[@ashutoshsingh-nu3fw]

why to make things complex.. You could have use directly equation of motion to explain. v*v=u*u+2as; BTW can't use energy conservation ..

[@glorymanheretosleep]

This kid is not an engineer...

[@EngineeringExplained]

Hahah maybe, though my feelings for electrical engineering are similar to yours. Honestly it's quite similar to mechanical when you break it down, but I didn't enjoy studying it at all. Perhaps I can get around to it eventually.

[@perumallaharishkumar3079]

Can we use v^2/mue *g

[@EngineeringExplained]

No worries, glad to hear!

[@EngineeringExplained]

Umm, perhaps. I'd recommend checking out my video "traction circle." May be what you're looking for. If not let me know more specifically what you're interested in.

[@omerkhan6247]

you can drive the equation through work energy theorem Fd=1/2mv2. where F=ma. very nice explanation by the way. thanks.

[@egeagustos585]

I am sad because I just found you. You are amazing, as I am an engineer, it has been great to listen you. Greetings from Turkey. Can you give the book name or any article that you take the equations :)

[@dragospahontu]

He's using one of the kinematic equations

[@njanirudh]

How can the tyres be prevented from getting locked while braking without the use of ABS or other circuitry. What are the parameters taken into account when designing against tyre locking ?

[@leganjan]

are you a mechanical engineer? you know a lot of crazy stuf :) you should definetly be professor. My profesor for Engines was awsome, but you are even better. I would like if you would give more car brand examples when talkin about some car parts. owerall you are doing awesome work, just don't stop

[@EngineeringExplained]

Test run, it's probably illegal for them to do it just from a calculation, unless they put an asterisk and say "estimated." It's probably impossible to account for every real world influence on braking distance mathematically, so real world testing is necessary.

[@EngineeringExplained]

Better tires! Haha, well I don't know. Carbon ceramics used in greater quantities for sure. It's a great relatively new technology. Also a friend of mine showed me an Audi wagon that used flower shaped disc brakes to shave off some extra weight. Thought that was cool.

[@EngineeringExplained]

At about 4:00 I explain how I got the equation.

[@AniketNevrekar]

Hey Jason. I'm revisiting this topic to improve my understanding. Considering only kinetic energy of the vehicle and this equation, when speed doubles, stopping distance should quadruple. How would stopping distance be affected if we considered downforce? Downforce should also increase with speed. So how will it affect braking distance? Will the stopping distance still be quadruple with double speed, if downforce is factored in?

[@paramveer1202]

This is a good video , I would also like to know how breaking distance is affected in case of abs mathematically.

[@sexyvsm]

perfect explanation Sir.. im very impressed about all your video and im gaining more knowledge in quick time.. thank you very much Sir.

[@oldfashionedwrx3574]

I see ABS as a performance enhancement for brakes, though many people over look reaction time, as 1 second reaction time could make a huge difference.

[@coolacoc1485]

Maybe you can create a video on this... what is better for the car.... braking slowly as you approach a light or braking right at the end when? Or are they both the same?

[@12233344445555532]

Can you do videos like these but on car audio? The concepts of impendence, peak power v.s. rms power are so confusing and our videos make the most complex systms of cars seem simple. So i was hoping you could work your magic and shed some light on car audio, specifically subwoofers and amps.

[@WannabeGearHead]

Now I have a question so when they give you the braking distance... are they actually doing it from a test run, or just by an equation like what you are showing us?

[@zanick2]

can you plug in the numbers of the slowing distance of a 3000lb vehicle vs a 3500lbs vehicle? (same tires ) does the Coef of friction go up? (mu).... if not, if we increase the weight (mass by 15%) does the stopping distance go up by 15% too?

[@janmlakar7524]

What about air drag. I was looking for an equation with the air drag included

[@quicksilver4000]

No mention of the effects of brake bias on stopping distances? Question: If a car with an 80/20 brake bias can brake at 1G, but then you shut off the rear brakes completely, what rate can you (negatively) accelerate at?

[@EngineeringExplained]

quicksilver4000 Depends on the weight distribution of the car, the height of the CG, and how well the front tire compound deals with load.

[@zanick2]

+quicksilver4000 if you have 1 g of decl, before the rear brake removal then you have about 25% more weight on the front tires and 25% less weight on the rear tires. the rear tires can only be effective to the weight (or force) on the ground, and that is equal to the weigiht on them. for a 4000lb car, that might be only 1000lbs, or 500lbs per tire, which is not much compared to the front tires, plus don't forget engine braking which can be over 100hp, (100ftlbs at 5300rpm) that , through a 2nd gear gear ratio can be near 700ftbls at the tries, or 350ftlbs each tire. with a mu of (1), that means that there is only 150ftlbs of braking that the rear brakes were contributing anyway.

[@bipul2138]

how to calculate the deceleration if the only data that has been provided is that the brake shoe applies a torque or "t" newton-metre on the disc or drum

[@Deki757]

Will the stronger brakes decrease the stopping distance in one single stop?

[@mikkelkirketerp4884]

Nice vid! The 2004-05 Volvo v60r and v70r have a braking distance of 118 ft. Not bad for a car that weighs that much :)

[@mrpmj00]

My base 2017 Corvette Stingray with manual transmission stops from 60-0 mph in 90 ft. The Corvette ZR1 stops in 88 ft. American Engineering.

[@chrisk9808]

mrpmj00 came here to say this. Many Lamborghini, however, have a distance of roughly 100. Which makes the Corvette even more impressive!

[@mrpmj00]

@@chrisk9808 On the fwy, my Corvette gets 36 mpg in Economy mode and 465 hp on tap. Range shows over 500 miles.

[@shubhamshukla5093]

sir,thank you for this video.its help me a lot.i just asking you that how can i install additional cutting brake in the rear wheels with a company of DIAGONAL DISK BRAKE ASSEMBLY already using for four wheels.there is the problem of pressure reduction and leaking at joint.please reply....

[@yco67]

the rear spoiler serves as an additional air brake at speeds beyond 200 km/h.. so it doesn't help braking from 100 to 0 to achieve 31.4m..

[@rallikas]

Is there a good one sentence answer to “Why does the stopping distance grow to the power of thee in regards to speed” or “why does the stopping distance grow 8 times when the speed grows 2 times”

[@gkalamv]

Curious to know. Are those equations being taught in highschool in america? I am greek and i've known them since i was 15 years old. Great video as always

[@bharat3254]

hey can you please explain how to calculate the braking force on each brake of a car ( is it just by multiplying the mass of vehicle with acceleration given in manual of car and then dividing by number of brakes i.e 4 )) and also please give the range in which braking force for a normal car lies.

[@sirrepairsalot4189]

Nobody talks about the coeffient of the brake pads/shoes themselves... How are to equate that?

[@baja2011]

this info is great. however can u please explain how can i choose the size of my disc brakes.

[@EngineeringExplained]

It does indeed! I haven't performed my own 60-0, but I know it's nothing special.

[@sciencematters1614]

If you have a car traveling at 60mph with normal family car brake pads, will it enduce less wear on the brake pads and rotors to stop quickly in a short distance or stop slowly over an extensive distance?

[@KevinHaroldSkinner]

+Jaden Kirura Stopping converts your kinetic energy into heat using friction. An oversimplification of the conservation of energy would tell us that this would give us the same amount of overall heat no matter how much time you took to stop. Stopping slowly over an extensive distance will not only give your brake system more time to air cool, it will also allow fluid friction from the air your pushing and your engine to help slow you down. It may also save a little wear and tear on the mental state of your passengers.

[@sciencematters1614]

+Kevin Skinner Yes, that is true of physics. But the variable is the composite material the brakes are made of. If racing brakes stop a car better when they're at higher temperatures then the composite material must be designed to absorb more energy at such temperatures. Since engineers can predict the temperature range of brake pads under certain conditions, my question restated can be: are brake pads designed to wear away less at high temperatures? If family car brake pads wear away more when they're cold then it wouldn't be beneficial to use extended stopping distance. If they wear less when they're warmer, then it'd be better to stop quicker.

[@SteveSmekar-ll6ln]

+Kevin Skinner You know, I used to drive forklift for a living and my ladyfriend expressed that stressed out principle as I would calculate my braking distance (also good at math) to stop 2-3 ft from the bumper of the vehicle I approached.Since then, I have uh, adjusted my mental calculations in the negative direction, if you will... figuring stop placement to be where I can see the rear tires of said vehicle.

[@foodguy6761]

If you are hauling a liquid how does it impact stopping distance?

[@PAVANKALYAN-yj8gl]

hello sir we guys are participating in a student competition called QUAD TORC .here i have query recently i watched your video regarding braking system so i wanted to how do i calculate lever travel for front braking system of a motorcycle..?

[@Carrera911Fan]

can you explain airbags ?

[@karthikbiker99]

just curious! y didnt u use this famous eq Vf^2 - Vi^2 = 2as ..? (s for distance)

[@InsomniaReview]

Is there a way of finding the breaking distance with the mass,Vi, Vf (Vf being 0) and the frictional force? thanks for the video though still helped me understand the concept a little better :)!

[@funnyvideogame9836]

how calculation braking torque

[@alial-ali865]

GREAT KNOWLEDGE

[@SuperHammerzeit]

I want to see braking distance on dry asphalt and plain ice for best new all-season tire, 10 years old studies winter tire, new summer tire and 10-years old summer tire.

[@EngineeringExplained]

F=ma, so a=F/m.

[@ritvikjain4119]

how can the coeffecient of friction be greater than 1??

[@Catrik]

Example: you have a cube that weights 1kg. So, to lift the cube up, you need to apply 1kg of force, right? Now if the cube is placed on a table, and the cof between the table and the cube is 0.5. This means, that to push the cube across the table, you need to use a force of 0.5kg IF the cof would be 2, it would mean that to push the cube, you need to use a force of 2kg. So in a sense coefficient of friction is just a multiplier of the weight of the object.

[@mftgdeserteagle]

Isn´t the equation x(t): v0t +(1/2)at^2 ? Where did you get that one from?

[@manasranjanmishra9258]

It's actually v²-u²=2as

[@oigres223]

what it the equation for solving for acceleration???????

[@olegkolgatin5279]

Thanks for your videos!:) Do you know how much powerful carbon/carbon brakes are (in their best temperatures of course) comparing to steel? And what about ceramic? I heard somewhere they are 30% more powerful than steel

[@BitchyBoxxy]

Ceramic can shatter

[@leviwilbert9588]

excellent, i have found my '11 xdrive35i has 0.991948 G's of stopping power. i am near to the force of gravity itself!!

[@EngineeringExplained]

It's on the list. :)

[@helloig5686]

Wait so i dont have to label the deceleration as having a negative value?

[@ShanePKing]

If you're not going to do much maths in the new videos I'm going back to these old ones.

[@ranger178]

does anyone actually have good test results of how a few pounds low or high on tire pressure affects stopping distance?

[@ahmednassar4414]

Braking distance = (kinetic energy)/(braking force) = 0.5 * mass * v^2 / (mass * acceleration) = 0.5*v^2 / acceleration

[@mftgdeserteagle]

Sorry I didn´t watch it till the end. It all makes sense now :)

[@zynthos9]

How does a spoiler increase downforce?

[@smarterworkout]

Zambia95 ...because the wind hits it. The faster - the more wind = more downforce. Less downforce the more the vehicle slows.

[@SzymekCRX]

That was pretty interesting

[@bharat3254]

Thanks I will be waiting.

[@MazdaGigante]

2021 Subaru WRX, 70mph to 0mph, equals 1.04G's based on Car and Driver's 70mph - 0 mph distance. Same with the 2021 WRX STI.

[@torijenna1629]

The main thing you need to know is that if a car brakes at less than 120MPH in a 60 to zero test than it is stopping at faster than 1 g ...and that is fast. The 2011 M3 stops in approximately 110 and the 2011 Mustang Gt at 108 ....approximately 1.1g based on this calculation!!!

[@manmeetsingh8115]

can u cleary explain how can we increase down force on car without increasing the weight of the car??

[@1971mgb]

Manmeet Singh down force and weight aren't the same thing A car sitting still has the weight of the car measured on the ground, body spoilers creat down force which pushes the car down on the road icreasing braking an F1 car slows greatly just from down force upon lifting off the throttle.More foenforce more grip better stopping .A formula 1 car can stop from 60mgh in 48feet 2.5G and that isn't at maximum down force

[@manmeetsingh8115]

1971mgb thank u sir, I would go through the point you mentioned.

[@lokesh.g2814]

My atv travelling at 40km/hr just stops at distance less than 3m. Why?

[@lfsracer79]

That doesn't sound very plausible. Maybe you should measure again.

[@yco67]

with the 1888kg curb weight how can Veyron Super Sport stops from 100km/h in 31.4m and 2.3 seconds? its amazing. !!

[@EngineeringExplained]

Search my channel, I have a video on ABS. Depending on the intelligence of the computer, and how many cycles it can pump the brakes in a second, a computer will likely out-brake a human in most scenarios.

[@smarterworkout]

I just have a hard time believing going 88ft/sec (60mph) it only takes 120 ft to stop. Thats pretty damn good braking.

[@busayoakanni]

The assumption was probably that the brakes work at 100% efficiency.

[@torogami2]

Braking distance is governed by the fun equation

[@1ohtaf1]

What would you consider as a recent innovation in braking systems?

[@rapzeh4]

meh, 2:17 am ain't the best time for a math vid XD

[@johnellison1635]

Is this your little brother? 😀

[@matthewgodwin5286]

Was doing 60 and stop in 40 feet cause deer was in front me and huge drop to my right I am glad had racing seat and harness cause of brute force I had high performance tires and brakes was worth every penny I tap the deer and both of us walked away me battered from seat belt

[@yco67]

np.. 1.3g with brakes + 0.6g with air brake = 1.9g if you hit the brakes at 300km/h.. hard to believe..

[@torijenna1629]

Sorry I meant less than 120 FT not MPH...duh..

[@EngineeringExplained]

haha don't encourage it!

[@Burhaan1977]

31.2.2021 👀

[@meonjeo]

Can anyone solve this ? Find the stoping distance if Vehicles weight = 300kg Speed 40km/hr Coefficient of friction of ground =0.8 Wheel dia= 566mm Width =177mm Consider all wheels locked

[@ipechman]

7.87 meters

[@chipsandcheesecurlz]

0:23 Do you mean American? Because the English use the Metric system, bro.

[@michaeldavis2531]

It's refereed to as "English Units" because these types of units originated in England. When the U.S. became independent in 1776, it inherited some of the English Units from the England, therefore they were referred to as English Units, they're formally known as "U.S. Customary Units," or just "Customary," or sometimes "Inch-Pound units," this saves confusion from the "British Imperial System," which was developed later in the U.K., and which the United States never used, and believe me, both systems have significant differences, and are not the same, especially in terms of volume, but even less so, length and mass. You're correct, England has used Metric units since 1965, and U.S. Customary Units are sometimes referred to as "English Units" because they were inherited from Great Britain when the United States became an independent country in 1776.

[@cheadeedoe2139]

A 6.0kg object undergoes an accelerate of 2m/s .What is the magnitude of the resultant.

[@kbj42016]

Once again: 0 Dislikes!

[@supeskrim]

Thumbs down for not using SI units.

[@KORTOKtheSTRONG]

YE OLDE ENGLISHE SYSTEME

[@glorymanheretosleep]

Something tells me you did it wrong.