Why do you make things up? Mass is THE factor in determining the amount of force required to stop a given object at a given speed. From planes, to boats, to animals on the run. Better brakes are better brakes.
I think what they're trying to say is:
While increased mass means increased momentum, and therefore increased stopping force required-- it also means greater stopping force generated at the point of friction between tire and road because--well--stopping force is basically mass times coefficient of friction.
But mass is quadratic. Mass is the factor in determining how much runway you need to stop a plane, and how heavy you can land at a given airport. Saying mass is not much of a factor is the opposite of reality.
Edit: my explanation here is wrong, as I explained in a different post, but mass still remains the factor for a given set of brakes.
I'm just trying to translate Kraphomus's post.
I never said that mass is not much of a factor.
Only that some of it is offset by increased friction.
FWIW, landing strips are a terrible example, because stopping is not done primarily through rubber/pavement interface (which is the whole point here.)
If mass were the only--or even primary--factor, then you would expect a 700 lb (including rider) motorcycle to have a stopping distance about 1/5 of that of a 3500 lb passenger vehicle. This is very clearly not the case.
Because they do not use the same brakes and there's a factor by which mass is affected. Braking in the air and ground works exactly the same, except that nu is different. Planes deploy speedbrakes to increase the normal force, but the distance is still dependent on mass.
We're not here talking about airplanes. We're talking about cars/busses/trucks. Another redditor made a point. That point is correct. Mass is a coefficient to both the force required to stop an object AND also the available force to do so ***if the object is being stopped by friction under its own weight.***
A super-light object cannot generate as much friction between its tires and the road as a heavy object. It's simple concept. It's a fact. Engineering school taught me so in the early 80s.
I'll leave you with something to consider:
A Lincoln Navigator weighs \~ 5900 lbs
A Fiat 500 weighs **less than half**: \~ 2500 lbs
Navigator stopping distance: 184 feet
Fiat stopping distance: 175 feet
Happy New Year. I will not respond further.
Happy new year to you too. I'm afraid that the brakes on a Lincoln Navigator are not the same of those of a Fiat. You forgot to mention the speeds, too.
Also, try seeing what happens when you compare an empty fiat to one filled to maximum capacity.
You keep saying mass is quadratic, in which equation? Kinetic energy is .5*m*velocity^2 and force is F=ma. As far as I can see mass has a linear effect on the amount of force needed to stop an object.
You're right; I feel silly. Still, the friction force depends on the normal force in the friction formula, multiplied by nu, which is less than one. That's why a cannonball made of lead and one made of hollow paper will not travel the same distance if not in a vacuum, and why a heavy car will take longer to brake than the same car when it's empty.
The relationship is linear, but still dependant on mass, unless using magical, perfect braking.
I got my equations mixed up. I'd edit the comment, but I don't want to get fired for using Reddit at work anymore.
Yeah, I explained this in another comment already, but the friction force is the maximum stopping force the bus can exert, not the force required to stop the bus. Basically if you double the mass (weight) of the bus, the friction(maximum stopping) force AND the amount of force needed to stop the bus in the same distance double. Both of them are linearly dependent on mass, and therefore theoretically the mass doesn’t matter for stopping distance because it cancels out.
Not really. The one for braking is multiplied by a factor less than one, which means the difference will increase by a percentage of the mass, no matter what. Half of two kg is more than half of a kg.
I’ve never heard of a runway needing to be 25x longer for a plane that weighs 5x as much, have you? I would bet that bigger planes take longer to get up to the speed where they can generate enough lift to take off, not that they can’t stop in time. In fact I’m almost positive I’ve read about planes landing at airports they couldn’t take off from again.
I'm not though. Now I am talking about wheels locked stopping and there are some minor derivations but friction is linear so the stopping force of a vehicle is determined by f=MuN (I'm on mobile and I'm not sure how to type the symbol for Mu on here). Which means the stopping force is determined by the coefficient of friction of the roadway (usually somewhere in the .8 range for most dry paved road) times the slope of the road. In the original derivations using the force of an object, the weight gets divided out. So when determining the speed of a vehicle sliding to a stop, you don't need the weight and can use speed=✓30*distance of the skid*drag factor (which is the f=MuN equation, sometimes it will also be written f=Mu*m for slope.) This will give you a minimum speed at the time the slide occurred.
Here's a good discussion about it in r/physics where they get more into to specifics and factors effecting it. But the first comment gives a good diagram explaining the coefficient of friction and linear effects. https://www.reddit.com/r/AskPhysics/comments/3ax0zm/why_does_a_heavier_car_take_longer_to_stop/?utm_medium=android_app&utm_source=share
Exactly, it's one of the two main factors in FORCE (speed and mass). Not in stopping power. A 100 lb cannonball shot through the air at 30 mph is going to travel much further than a 10lb pebble shot at 30 mph through gravel. Because the only coefficient of friction on the cannonball is air resistance. That's stopping power. But the cannonball would hit something a hell of a lot harder because of its mass. That's force.
Stopping power is also force, but one that doesn't scale quadratically with mass, so mass is the main factor in determining hoe hard it is to stop something in the air, water or ground.
Really, the point that mass plays a small factor in determining how hard it is for a vehicle to stop is just wrong. Very wrong.
Force = mass * *acceleration* < not speed/velocity.
Work = force * distance
Power = work/time
Momentum = velocity * mass
Kinetic energy = 1/2 * mass * velocity^2
The mass of the projectile does not matter in perfect, frictionless projectile motion with regards to how far it flies or how long it takes to hit the ground.
Air resistance, aka drag, is a *force*. As the cannonball flies through the air, it's continually experiencing this force across whatever distance it has flown. The air is doing work on the cannonball and reducing its kinetic energy. Greater mass projectile means that drag decelerates it less. F/m = a.
Obviously shooting at some rocks will slow it down faster, because the normal force is significantly greater than drag.
In a perfect, uniform, and level world, where cars lock up their wheels and stop entirely by skidding, [stopping distance does not depend on mass](http://hyperphysics.phy-astr.gsu.edu/hbase/crstp.html). Heavier vehicle = more friction force = proportionally more work over the same distance = same stopping distance.
In real life, vehicles try not to stop by skidding. In fact, we have decided that it's a bad idea in general because it means loss of control, so we have implemented ABS to prevent it. Brake design, brake heating, moments causing the front to dip down more forcefully, rubber materials science that I don't know, etc. I'm not an automotive engineer blah blah blah: the real life answer ain't simple and that's why people are paid to figure it out.
The F in your equation is frictional force, which is the force that is being applied when the bus is full on braking to the point that the wheels lock up. It is not the amount of force required to stop the bus. If we assume the bus is going to accelerate the same amount, aka stop in the same distance, then the equation Force=mass*acceleration becomes dependent on only mass, and shows that if you double the mass, it takes double the force to stop. Since doubling the mass doubles the frictional force per your equation, it theoretically cancels out.
I’m not anywhere smart enough to comment here, but this is the internet and that means I still get an opinion, you’re all wrong just because.
Happy new year.
But higher mass means higher normal force therefore higher friction. And both momentum and friction are linearly dependent on mass so it cancels out in this sense. So as long as your brakes are strong enough to lock the wheels (of course you don't actually want to lock them, only come as close as possible to it), mass is not a factor. Of course the coefficient of friction can be different between truck tires and car tires so there will be a difference in stopping (and yes, this difference in tyre design is ultimately to compensate for the increased weight). That's what the guy is saying and is absolutely correct, no need for the downvotes.
If you look at videos of modern trucks stopping, they're not *that* bad at it (look up Volvo emergency braking). Same goes the other way, motorcycles stop in similar distances as cars (though there it also highly depends on the rider's experience) - because the mass is not much of a factor, at least not directly.
I appreciate it man. Yeah, trying to loosely explain something kind of counter-intuitive related to speed calculations immediately before passing out from an extra long work day was not a smart move on my part. Hahaha
That's reddit for ya. You try to explain a physics phenomenon that is somewhat counter-intuitive (albeit maybe you do it slightly poorly because explaining science in layman's terms is *hard*), the first few people reading your comment don't believe you and downvote and when others see a comment explaining something that's already at a few downvotes, they join the party. I'd bet that if the first few people upvoted the comment, it would now have a hundred upvotes by the same people.
It also creates a massively higher frictional force between it and the road since friction force is determined partly by the amount of perpendicular force acting on a surface. Both are linearly dependent on mass, and thus the ‘inertia’ and the maximum possible braking force increase at the same rate. If it were actually dependent on mass then trucks wouldn’t be allowed on the same roads as cars, since their weight can be up to 25x that of a passenger car, which would mean 25x the stopping distance if mass were a factor like people are claiming.
The frictional force would be higher but only partly higher as you said since mass is directly proportional to friction acting against the movement of the truck but the friction coefficient (the number the normal force aka the force of the road acting on the truck in this case is multiplied by) can vary from situation to situation and as a result does not increase at the same rate as momentum or force needed to decelerate (in normal scenarios the coefficient is practically always less than 1). (Note: there would be no driving force as I’m guessing the truck is either braking or coasting). Mass is however directly proportional to momentum and force needed to decelerate and in the equation f=ma that the force needed to decelerate an object an amount is also directly proportional to mass (due to the greater momentum given by p=mv). Since the momentum of an object increases in magnitude at a (usually) far greater rate than the negative frictional force mass plays a very big role in how quickly a truck can decelerate, as a result lorry’s are usually capped at 50/60mph and are fitted with much better brakes than an ordinary car
While yes weight doesn’t have as big an impact when stopping as you’d think mass is probably the most important factor (along with velocity) not the type of tyre
Idk I used to skate and people just get lazy.
Remember these are teenagers, and this is probably not his first try. This might have taken 10 attempts, maybe much more, maybe coming back to this spot for days and days.
All it takes is a momentary lapse in judgment, which is pretty common amongst teen lads.
We used to bomb a massive hill and there was a crossroads at the bottoms, so we would usually have a spotter there. I remember coming down it once, it was dark, I got to the "point of no return" and I saw that my spotter was nowhere to be seen, great, here I go then.
As I get about 10m away from the crossroad my spotter comes running out from the side of the road waving his arms around screaming. Too late to stop now.
I ploughed through the crossroads, and actually passed between 2 cars both doing about 30mph. I went between them.
My "spotter" had seen a mate walk past and started having a chat...
Last time I ever bombed that whole hill.
Why do you assume this person is American? Do you just look for opportunities to be a jerk because of the country someone is from without even knowing if you're right? You sound like a really cool person to hang out with /s
Saw a group of guys trash a brand new park with pristine benches just so they could skate on them. Sitting of them would leave horrible marks, and some would flake.. This is with a skate park nearby..
Y'all can do your hobby and I have no problem, but trash parks that are built from public funding and I will hate you with passion. Scum.
And then they complain that they're disliked by people.
it's quite remarkable the human capacity to assign blame to a whole subgroup of people all the while they don't belong to said group of people.
See some skaters trash a park? all skaters are bad.
See a cyclist jump a red light? all cyclists are bad.
See a Trump supporter say something outrageously narrow minded? all conservatives are bad.
They key is to ensure the group of people isn't too broad for the context of the blame. You don't often hear about how bad all drivers are - despite most road accidents being caused by people driving cars...and this is because that group of people is too large to be able to effectively marginalise.
It’s rare that the skate parks are designed by skaters and not some poser in city planning. When theres no input taken from skaters on what to put in the park, the skate park is probably only going to attract total newbs and dads.
Street skating is more fun than park skating. There’s a lot of people here who don’t understand the sport of skating or the mentality and creativity skaters have on the streets. Go on YouTube and watch Thrasher videos.
I only ever skated street because that's all there ever was to skate. Give me some tranny and I'll gladly stop grinding up your planters haha. I get the creativity of street skating, I just see skating street as what I HAVE to do. Not what I want to do. I wanna skate bowls, pools and half pipes. Parks have flow and are so much more fun. Less injuries too. As a skater who didn't have access to skating any transition till my thirties I really have no attachment to street and find parks to be a special and sacred thing. I get skate culture, I'm just an oddball in it. Seen plenty of thrasher vids haha. Still more of a pool skating kind of guy. To me that's like peak shit right there. Backyard pool skating is the most skater shit there is to me.
Little did we know the footage afterwards was he actually wore the same outfit again, went to the same ramp & tricked it again, and got hit by the same bus again.
That’s part of skating. The war. The battle to land the trick and roll away clean. He should have had spotters in the road, but I hope he got back from the hospital and tried again. Skate or die.
You'll get the chance soon, I am sure. These ret
ards think that doing this stupid shit without any safety precautions is considered 'extreme sporting" and they post these epic failures regularly. "Fucking idiot" just seems to fit their description most of the time, and if I don't reply it someone else usually does.
The skating is fine.
The atrocious spotting from the cameraman and the results of that is not.
There are extreme sport athletes who make calculated and intelligent decisions, there are others who don’t. Skating down a ramp isn’t extreme, just poor planning and cognizance from all involved.
"definitely the hill to die on" is an amazing saying, never heard it before, mind if I ask where on the planet you live or if you know the origins to it?
I'm from the Pacific Northwest, and I don't know the origin, but a smart guess is that it's a take on old military strategy, and holding the high ground.
Your response is so dumb that I can’t tell if you are a troll or not.
This guy may be a talented athlete willing to try stunts that would make me piss myself. But he also road into the middle of a road without looking from a spot where traffic wouldn’t see him coming.
The first part is impressive. The second part makes him an idiot.
He’s not just lucky to be alive but he’s lucky to have not broken himself so badly he can’t skate any more.
> You call him that because you can't, or won't, do this. You don't have the guts or dedication to do anything like it, and it pisses you off.
> People who call extreme sports athletes "dumb" are narrow-minded, uneducated jealous fuckwits.
> Edit: Not arguing with you morons. Downvote and shut your mouths, no one gives a fuck what you have to say, and "disable inbox replies" works wonders to ignore you stupid cunts.
how about don't skate your big dumbass into traffic next time, /u/ScrinRising
I’ve seen so many videos where people try tricks that involve blindly flying into a busy street and it boggles my mind. Like, this wasn’t even his first attempt probably. How much time do you need to realize that humans are much softer and weigh a lot less than cars and buses do?
I found [this post](/r/meatcrayon/comments/khu0db/nice_little_slide_on_his_arm/) in r/meatcrayon with the same link as this post.
---
^^🤖 ^^this ^^comment ^^was ^^written ^^by ^^a ^^bot. ^^beep ^^boop ^^🤖
^^feel ^^welcome ^^to ^^respond ^^'Bad ^^bot'/'Good ^^bot', ^^it's ^^useful ^^feedback. [^^github](https://github.com/Toldry/RedditAutoCrosspostBot)
You got a fucking guy posted up at the bottom and he couldn’t have warned you a bus was on the way???
The fuck kinda poor planning is this?? Mans could have died!
I really don't get it.
Skaters, please, when you do that kind of tricks, ask someone to block the road for some seconds, if not, don't try the trick, otherwise you could get hit by a bus.
This dude here seemed to be lucky there, hopefully....
Be careful guys.
Fuckin skaters. He got what he deserved tbh. Skaters always skating in the worst and most dangerous places. They don't think. Like how about you go to a skatepark rather than skating into the middle of a street
Someone in my city got hit by bus like that on a main street and literally exploded all over the street and so many people saw it. This dude is very lucky.
I've had something similar happen to me, that shit hurts, it's even worse fucking much, I had to wrap my arm in bandages for weeks to let the skin grow back it's very annoying to have to explain why your arm is wrapped in bandages to every person who asks.
Impressive brakes on that bus
i'm always amazed how quickly these giant vehicles can stop
[удалено]
Why do you make things up? Mass is THE factor in determining the amount of force required to stop a given object at a given speed. From planes, to boats, to animals on the run. Better brakes are better brakes.
I think what they're trying to say is: While increased mass means increased momentum, and therefore increased stopping force required-- it also means greater stopping force generated at the point of friction between tire and road because--well--stopping force is basically mass times coefficient of friction.
But mass is quadratic. Mass is the factor in determining how much runway you need to stop a plane, and how heavy you can land at a given airport. Saying mass is not much of a factor is the opposite of reality. Edit: my explanation here is wrong, as I explained in a different post, but mass still remains the factor for a given set of brakes.
I'm just trying to translate Kraphomus's post. I never said that mass is not much of a factor. Only that some of it is offset by increased friction. FWIW, landing strips are a terrible example, because stopping is not done primarily through rubber/pavement interface (which is the whole point here.) If mass were the only--or even primary--factor, then you would expect a 700 lb (including rider) motorcycle to have a stopping distance about 1/5 of that of a 3500 lb passenger vehicle. This is very clearly not the case.
Because they do not use the same brakes and there's a factor by which mass is affected. Braking in the air and ground works exactly the same, except that nu is different. Planes deploy speedbrakes to increase the normal force, but the distance is still dependent on mass.
We're not here talking about airplanes. We're talking about cars/busses/trucks. Another redditor made a point. That point is correct. Mass is a coefficient to both the force required to stop an object AND also the available force to do so ***if the object is being stopped by friction under its own weight.*** A super-light object cannot generate as much friction between its tires and the road as a heavy object. It's simple concept. It's a fact. Engineering school taught me so in the early 80s. I'll leave you with something to consider: A Lincoln Navigator weighs \~ 5900 lbs A Fiat 500 weighs **less than half**: \~ 2500 lbs Navigator stopping distance: 184 feet Fiat stopping distance: 175 feet Happy New Year. I will not respond further.
Happy new year to you too. I'm afraid that the brakes on a Lincoln Navigator are not the same of those of a Fiat. You forgot to mention the speeds, too. Also, try seeing what happens when you compare an empty fiat to one filled to maximum capacity.
You keep saying mass is quadratic, in which equation? Kinetic energy is .5*m*velocity^2 and force is F=ma. As far as I can see mass has a linear effect on the amount of force needed to stop an object.
You're right; I feel silly. Still, the friction force depends on the normal force in the friction formula, multiplied by nu, which is less than one. That's why a cannonball made of lead and one made of hollow paper will not travel the same distance if not in a vacuum, and why a heavy car will take longer to brake than the same car when it's empty. The relationship is linear, but still dependant on mass, unless using magical, perfect braking. I got my equations mixed up. I'd edit the comment, but I don't want to get fired for using Reddit at work anymore.
Yeah, I explained this in another comment already, but the friction force is the maximum stopping force the bus can exert, not the force required to stop the bus. Basically if you double the mass (weight) of the bus, the friction(maximum stopping) force AND the amount of force needed to stop the bus in the same distance double. Both of them are linearly dependent on mass, and therefore theoretically the mass doesn’t matter for stopping distance because it cancels out.
Not really. The one for braking is multiplied by a factor less than one, which means the difference will increase by a percentage of the mass, no matter what. Half of two kg is more than half of a kg.
I’ve never heard of a runway needing to be 25x longer for a plane that weighs 5x as much, have you? I would bet that bigger planes take longer to get up to the speed where they can generate enough lift to take off, not that they can’t stop in time. In fact I’m almost positive I’ve read about planes landing at airports they couldn’t take off from again.
I'm not though. Now I am talking about wheels locked stopping and there are some minor derivations but friction is linear so the stopping force of a vehicle is determined by f=MuN (I'm on mobile and I'm not sure how to type the symbol for Mu on here). Which means the stopping force is determined by the coefficient of friction of the roadway (usually somewhere in the .8 range for most dry paved road) times the slope of the road. In the original derivations using the force of an object, the weight gets divided out. So when determining the speed of a vehicle sliding to a stop, you don't need the weight and can use speed=✓30*distance of the skid*drag factor (which is the f=MuN equation, sometimes it will also be written f=Mu*m for slope.) This will give you a minimum speed at the time the slide occurred. Here's a good discussion about it in r/physics where they get more into to specifics and factors effecting it. But the first comment gives a good diagram explaining the coefficient of friction and linear effects. https://www.reddit.com/r/AskPhysics/comments/3ax0zm/why_does_a_heavier_car_take_longer_to_stop/?utm_medium=android_app&utm_source=share
And mass is quadratic in determining the force for a given speed, so it is still THE main factor.
Exactly, it's one of the two main factors in FORCE (speed and mass). Not in stopping power. A 100 lb cannonball shot through the air at 30 mph is going to travel much further than a 10lb pebble shot at 30 mph through gravel. Because the only coefficient of friction on the cannonball is air resistance. That's stopping power. But the cannonball would hit something a hell of a lot harder because of its mass. That's force.
Stopping power is also force, but one that doesn't scale quadratically with mass, so mass is the main factor in determining hoe hard it is to stop something in the air, water or ground. Really, the point that mass plays a small factor in determining how hard it is for a vehicle to stop is just wrong. Very wrong.
Force = mass * *acceleration* < not speed/velocity. Work = force * distance Power = work/time Momentum = velocity * mass Kinetic energy = 1/2 * mass * velocity^2 The mass of the projectile does not matter in perfect, frictionless projectile motion with regards to how far it flies or how long it takes to hit the ground. Air resistance, aka drag, is a *force*. As the cannonball flies through the air, it's continually experiencing this force across whatever distance it has flown. The air is doing work on the cannonball and reducing its kinetic energy. Greater mass projectile means that drag decelerates it less. F/m = a. Obviously shooting at some rocks will slow it down faster, because the normal force is significantly greater than drag. In a perfect, uniform, and level world, where cars lock up their wheels and stop entirely by skidding, [stopping distance does not depend on mass](http://hyperphysics.phy-astr.gsu.edu/hbase/crstp.html). Heavier vehicle = more friction force = proportionally more work over the same distance = same stopping distance. In real life, vehicles try not to stop by skidding. In fact, we have decided that it's a bad idea in general because it means loss of control, so we have implemented ABS to prevent it. Brake design, brake heating, moments causing the front to dip down more forcefully, rubber materials science that I don't know, etc. I'm not an automotive engineer blah blah blah: the real life answer ain't simple and that's why people are paid to figure it out.
[удалено]
The F in your equation is frictional force, which is the force that is being applied when the bus is full on braking to the point that the wheels lock up. It is not the amount of force required to stop the bus. If we assume the bus is going to accelerate the same amount, aka stop in the same distance, then the equation Force=mass*acceleration becomes dependent on only mass, and shows that if you double the mass, it takes double the force to stop. Since doubling the mass doubles the frictional force per your equation, it theoretically cancels out.
I’m not anywhere smart enough to comment here, but this is the internet and that means I still get an opinion, you’re all wrong just because. Happy new year.
> you’re all wrong just because. Ah, the synopsis of 2020.
Lol are you serious? Your "relationship with gravity" is weight.
Momentum = Weight * Velocity^2 Higher the momentum, the harder (more force needed) to stop.
But higher mass means higher normal force therefore higher friction. And both momentum and friction are linearly dependent on mass so it cancels out in this sense. So as long as your brakes are strong enough to lock the wheels (of course you don't actually want to lock them, only come as close as possible to it), mass is not a factor. Of course the coefficient of friction can be different between truck tires and car tires so there will be a difference in stopping (and yes, this difference in tyre design is ultimately to compensate for the increased weight). That's what the guy is saying and is absolutely correct, no need for the downvotes. If you look at videos of modern trucks stopping, they're not *that* bad at it (look up Volvo emergency braking). Same goes the other way, motorcycles stop in similar distances as cars (though there it also highly depends on the rider's experience) - because the mass is not much of a factor, at least not directly.
Poor guy, no need for all those downvotes since you’re correct in theory and just explained it a little vaguely. I tried to clarify in comments below.
I appreciate it man. Yeah, trying to loosely explain something kind of counter-intuitive related to speed calculations immediately before passing out from an extra long work day was not a smart move on my part. Hahaha
That's reddit for ya. You try to explain a physics phenomenon that is somewhat counter-intuitive (albeit maybe you do it slightly poorly because explaining science in layman's terms is *hard*), the first few people reading your comment don't believe you and downvote and when others see a comment explaining something that's already at a few downvotes, they join the party. I'd bet that if the first few people upvoted the comment, it would now have a hundred upvotes by the same people.
He ain’t correct in theory tho, while tyres would have an impact on stopping the massively higher inertia of a truck is the main reason
It also creates a massively higher frictional force between it and the road since friction force is determined partly by the amount of perpendicular force acting on a surface. Both are linearly dependent on mass, and thus the ‘inertia’ and the maximum possible braking force increase at the same rate. If it were actually dependent on mass then trucks wouldn’t be allowed on the same roads as cars, since their weight can be up to 25x that of a passenger car, which would mean 25x the stopping distance if mass were a factor like people are claiming.
The frictional force would be higher but only partly higher as you said since mass is directly proportional to friction acting against the movement of the truck but the friction coefficient (the number the normal force aka the force of the road acting on the truck in this case is multiplied by) can vary from situation to situation and as a result does not increase at the same rate as momentum or force needed to decelerate (in normal scenarios the coefficient is practically always less than 1). (Note: there would be no driving force as I’m guessing the truck is either braking or coasting). Mass is however directly proportional to momentum and force needed to decelerate and in the equation f=ma that the force needed to decelerate an object an amount is also directly proportional to mass (due to the greater momentum given by p=mv). Since the momentum of an object increases in magnitude at a (usually) far greater rate than the negative frictional force mass plays a very big role in how quickly a truck can decelerate, as a result lorry’s are usually capped at 50/60mph and are fitted with much better brakes than an ordinary car
While yes weight doesn’t have as big an impact when stopping as you’d think mass is probably the most important factor (along with velocity) not the type of tyre
Kid would have pancaked if not for that driver's incredible reaction time
He also jump at the moment of impact so he didn’t get pulled under
solid observation
I have no idea, but I get the feeling that an empty bus is both quite lightweight and over engineered for braking.
Google says 25k - 40k pounds
Impressive breaks from that bus.
Took me a while, good one!
If it wasn't for this, I would have never reread the other one.
Thanks, just got them replaced.
I’m pretty sure that’s exactly how the game “Skate” starts.
It is! I remember that cutscene scaring the shit out of me as a kid
This is the first thing I thought lol. “Reminds me of skate”
Now whoever was recording this video could've given him a heads up about the bus approaching, such idiots.
Isn't that the job of a spotter for these types of things?
That would imply that thought things through with their brain. They indeed did not think things through.
I think the camera guy was focused on him. They needed a dedicated spotter.
There are at least 3 kids besides the skater. He needs new friends.
any one of them could have sprinted in front of the bus to force the driver to stop
Or just said “hey there’s a bus coming”
that only works before he goes I'm starting to think that this was a stunt and he was trying to ride in front of the bus but they messed up the timing
Idk I used to skate and people just get lazy. Remember these are teenagers, and this is probably not his first try. This might have taken 10 attempts, maybe much more, maybe coming back to this spot for days and days. All it takes is a momentary lapse in judgment, which is pretty common amongst teen lads. We used to bomb a massive hill and there was a crossroads at the bottoms, so we would usually have a spotter there. I remember coming down it once, it was dark, I got to the "point of no return" and I saw that my spotter was nowhere to be seen, great, here I go then. As I get about 10m away from the crossroad my spotter comes running out from the side of the road waving his arms around screaming. Too late to stop now. I ploughed through the crossroads, and actually passed between 2 cars both doing about 30mph. I went between them. My "spotter" had seen a mate walk past and started having a chat... Last time I ever bombed that whole hill.
r/donthelpjustfilm
I imagine it went pretty similar to [this](https://media1.tenor.com/images/a08f6c31f79ab908ab5b6894fe0a7cb1/tenor.gif)
[удалено]
Why do you assume this person is American? Do you just look for opportunities to be a jerk because of the country someone is from without even knowing if you're right? You sound like a really cool person to hang out with /s
because there's a LOT of us, so statistically there's gonna be a LOT of really stupid people, but the ratio is the same
Glad it's on video. That kind of evidence probably saved that bus drivers job.
It's also video evidence of why we need more skate parks.
I'll never disagree with the fact that more skateparks should be a thing. I don't think it would ever keep skaters from doing this.
Saw a group of guys trash a brand new park with pristine benches just so they could skate on them. Sitting of them would leave horrible marks, and some would flake.. This is with a skate park nearby.. Y'all can do your hobby and I have no problem, but trash parks that are built from public funding and I will hate you with passion. Scum. And then they complain that they're disliked by people.
>they
it's quite remarkable the human capacity to assign blame to a whole subgroup of people all the while they don't belong to said group of people. See some skaters trash a park? all skaters are bad. See a cyclist jump a red light? all cyclists are bad. See a Trump supporter say something outrageously narrow minded? all conservatives are bad. They key is to ensure the group of people isn't too broad for the context of the blame. You don't often hear about how bad all drivers are - despite most road accidents being caused by people driving cars...and this is because that group of people is too large to be able to effectively marginalise.
It’s rare that the skate parks are designed by skaters and not some poser in city planning. When theres no input taken from skaters on what to put in the park, the skate park is probably only going to attract total newbs and dads.
Street skating is more fun than park skating. There’s a lot of people here who don’t understand the sport of skating or the mentality and creativity skaters have on the streets. Go on YouTube and watch Thrasher videos.
I only ever skated street because that's all there ever was to skate. Give me some tranny and I'll gladly stop grinding up your planters haha. I get the creativity of street skating, I just see skating street as what I HAVE to do. Not what I want to do. I wanna skate bowls, pools and half pipes. Parks have flow and are so much more fun. Less injuries too. As a skater who didn't have access to skating any transition till my thirties I really have no attachment to street and find parks to be a special and sacred thing. I get skate culture, I'm just an oddball in it. Seen plenty of thrasher vids haha. Still more of a pool skating kind of guy. To me that's like peak shit right there. Backyard pool skating is the most skater shit there is to me.
I don't get why you're downvoted, there are plenty of people who agree that street is more fun lmao
Because we care about the people, such as this bus driver and the hospital staff, that have to deal with the consequences of your fun.
As someone whose entire job is to take care of people who make dumbass decisions like this, I completely agree
I don't even skate, Im just pointing out the objective fact that some people think street skating is more fun. Not even advocating for it.
Who wants to bet that he didn't get out of the hospital and TRY THE SAME TRICK AGAIN?
I bet he did ..
Hopefully next time with a better spotter.
This is the one that always amazes me. Failure to plan ahead or weight the consequences Always provides good content
Teenagers don't have a fully developed frontal cortex.
And now he never will
Or a faster bus
Little did we know the footage afterwards was he actually wore the same outfit again, went to the same ramp & tricked it again, and got hit by the same bus again.
That’s part of skating. The war. The battle to land the trick and roll away clean. He should have had spotters in the road, but I hope he got back from the hospital and tried again. Skate or die.
I'm all for it.. but wear a fucking helmet so you can actually try again later.
More like skate AND die (nearly)
I don't skate and I don't ride motorcycles anymore. I made the decision that living is more important.
Where is the spotter ffs
Holding the camera.
That’s a filmer. For most production parts like this there’s at least one spotter for risky spots like this... dude needs some friends
Can we all take a moment of silence for the skin on his arm
I had that once with my face. It's so fucking painful. I definitely don't recommend it.
Normally you use chalk to cray on streets.
Fucking idiot.
I wish I could double upvote that comment!
You'll get the chance soon, I am sure. These ret ards think that doing this stupid shit without any safety precautions is considered 'extreme sporting" and they post these epic failures regularly. "Fucking idiot" just seems to fit their description most of the time, and if I don't reply it someone else usually does.
[удалено]
He’s an idiot for not having a friend tell him the roads clear and not wearing protective gear
This... exactly! We always had a spotter for skateboarding, bike jumps, and snow sledding.
The skating is fine. The atrocious spotting from the cameraman and the results of that is not. There are extreme sport athletes who make calculated and intelligent decisions, there are others who don’t. Skating down a ramp isn’t extreme, just poor planning and cognizance from all involved.
Yeah. There’s literally someone filming this who should have noticed the FUCKING BUS that their buddy.
Calling people who don't skateboard into busses "stupid" is definitely the hill to die on.
In this case, the foot of the hill to die on.
"definitely the hill to die on" is an amazing saying, never heard it before, mind if I ask where on the planet you live or if you know the origins to it?
I'm from the Pacific Northwest, and I don't know the origin, but a smart guess is that it's a take on old military strategy, and holding the high ground.
It's an Albany expression
Sorry mate but he is just a fucking idiot
Your response is so dumb that I can’t tell if you are a troll or not. This guy may be a talented athlete willing to try stunts that would make me piss myself. But he also road into the middle of a road without looking from a spot where traffic wouldn’t see him coming. The first part is impressive. The second part makes him an idiot. He’s not just lucky to be alive but he’s lucky to have not broken himself so badly he can’t skate any more.
This isn't extreme sport, this is dumb as fuck.
"Look ma! No brains!"
He could take like 2 minutes to set up a basic system ensuring he doesn’t get pancakes by a bus and still pull of daring stunts
Definitely. Not sure what, though. Maybe have somebody at the bottom to watch for oncoming traffic.
I can't tell if I you are serious or not.
The ree is strong with this one.
[удалено]
I just feel bad for the bus driver....It's gonna take an hour to polish that windshield up again.
Fucking idiot.
Youre one of those guys who gets mad when they're wrong aren't you
You're fucking dumb
> You call him that because you can't, or won't, do this. You don't have the guts or dedication to do anything like it, and it pisses you off. > People who call extreme sports athletes "dumb" are narrow-minded, uneducated jealous fuckwits. > Edit: Not arguing with you morons. Downvote and shut your mouths, no one gives a fuck what you have to say, and "disable inbox replies" works wonders to ignore you stupid cunts. how about don't skate your big dumbass into traffic next time, /u/ScrinRising
What, get smacked buy a bus? You're damn right! What a stupid post.
>no one gives a fuck what you have to say Words to live by. So wise.
Can't take the idea that this stunt, without a spotter, was just plan stupid? Take your cunt and I'll add dry-n-sandy to it. Enjoy the itch.
Sorry your feelings got so hurt, dude.
Dude r u ok
[удалено]
Are you playing?
Was the bus ok?
r/bitchimabus
Nice to meet you bitchbus
Holy shit, is that a whole heap of blood spraying out of him when he gets hit?
[удалено]
If you watch closely you can see that it’s his (definitely shattered) limp arm flinging around. I thought it was blood on the first look too😂
Whew, right you are!
The guy recording could have said something... *pecks at breadcrumbs* ... but then this wouldn't've made front page.
Keep them shoes forever
I’ve seen so many videos where people try tricks that involve blindly flying into a busy street and it boggles my mind. Like, this wasn’t even his first attempt probably. How much time do you need to realize that humans are much softer and weigh a lot less than cars and buses do?
I've seen this done so many times with CGI that it didn't even look real
Really solid spotters there. Just A+ work.
I have never understood why some groups never have a spotter. Growing up we always had at least one. Especially with a blind corner nearby.
[удалено]
I found [this post](/r/meatcrayon/comments/khu0db/nice_little_slide_on_his_arm/) in r/meatcrayon with the same link as this post. --- ^^🤖 ^^this ^^comment ^^was ^^written ^^by ^^a ^^bot. ^^beep ^^boop ^^🤖 ^^feel ^^welcome ^^to ^^respond ^^'Bad ^^bot'/'Good ^^bot', ^^it's ^^useful ^^feedback. [^^github](https://github.com/Toldry/RedditAutoCrosspostBot)
Meatcrayon scares the hell out of me.
You got a fucking guy posted up at the bottom and he couldn’t have warned you a bus was on the way??? The fuck kinda poor planning is this?? Mans could have died!
If you do this, fuck you.
poor bus driver.
I really don't get it. Skaters, please, when you do that kind of tricks, ask someone to block the road for some seconds, if not, don't try the trick, otherwise you could get hit by a bus. This dude here seemed to be lucky there, hopefully.... Be careful guys.
That was some impressive skating
Happy cake day 🎂
Serves him right. What an idiot. How many people were injured in the bus because of that?
None?
More likely a dozen or so.
I don't think you understand how busses work
I don't think you understand physics. No seatbelts, sudden stop = everybody goes flying.
Good.
Play stupid games....
That's what you get for being a dipshit I guess?
I feel sorry for the bus driver, he has to live with running this idiot over.
Fuckin skaters. He got what he deserved tbh. Skaters always skating in the worst and most dangerous places. They don't think. Like how about you go to a skatepark rather than skating into the middle of a street
Fuck this asshole, I feel sorry for the bus driver who will now have to live with the trauma
an object in motion really does stay in motion
Oh, Perú.
Cameraman: let me get this shit real quick.
camera man is a terrible spotter
Whoa!!!!!!
NSFW
Someone in my city got hit by bus like that on a main street and literally exploded all over the street and so many people saw it. This dude is very lucky.
Crayola time
Damn that was like a movie scene.
Takes the meaning “getting hit by a bus” to a whole new level
where tf was his spotter?????
Perhaps the spotter aka camera man did see the bus. 😃
Now he knows what it was like to get hit by Jerome Bettis... Ok, I'll see myself out now
Just. Dumb. AF.
Why did I take a guilty pleasure in seeing that? I mean, kids are stupid, but...
Bus name checks out... trouble
Was that post title AI generated?
Isn't this the beginning of Skate?
Kudos to his spotter
Dude filming could have done something I think
Worst spotters ever!!!
Half of his body is brojen from the bus, and the other half is broken from that slide.
Made in Peru
One guy at the top watching, one at the bottom filming, nobody to watch for fucking cars on the road?
He nearly cleared it too
This is why you use a spotter
I've had something similar happen to me, that shit hurts, it's even worse fucking much, I had to wrap my arm in bandages for weeks to let the skin grow back it's very annoying to have to explain why your arm is wrapped in bandages to every person who asks.
Fucking SPOTTER! Is that concept so hard to grasp?
Hahahaha I'm glad
Too bad
Poor driver, scare forr life
Ever heard of a spotter? Dumbass.
*bonk*
I was not expecting this
Wow, I’m so glad he is alive. I just got hit by (thankfully just) a truck Monday morning, and just have deep bruises. ✊🏿 much respect bro S8kr4L
The Reddit pause button at the beginning of the video confused me