Reel Physics: True Lies - Motorcycle Jump

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By the way, it is a little jarring to see the missing dash in the show's description:

"Two wise physics minded guys take movies and test their crazy shenanigans."

Should be "physics-minded".

I am never going to stop bugging you about this just because I love your show so much damn much combined with your obvious consideration of feedback and in depth replies to your fanbase.

What are the general physics behinds the robots in Reel Steel, the Mechs in Pacific Rim, and the Powered Armor Platform in District 9? How much power would it take to move them, the actual torque required from the joints,the amount of stress they place on themselves and the ground, what would they look like with current technology and its limitations, what technology would have to first be invented, etc? I know you could make an amazing episode out of each one given their vastly different scales, purposes, and the theoretical technology behind them.

Hell, maybe one day if you become popular enough and have the time branch off into the speculative realm of video games and the physics behind them and their cutscenes. :D No shortage of content there suggested by a possible fanbase that's OVER 9.8 THOUSAND!!!!!!!!!! squared.

Really nice show, enjoyed it!
Please keep using the SI units though! (As a physicist myself, last episode irritated me beyond belief ;) )
Keep up the great work!

Really nice show, enjoyed it!
Please keep using the SI units though! (As a physicist myself, last episode irritated me beyond belief ;) )
Keep up the great work!

Saulkar:
I am never going to stop bugging you about this just because I love your show so much damn much combined with your obvious consideration of feedback and in depth replies to your fanbase.

What are the general physics behinds the robots in Reel Steel, the Mechs in Pacific Rim, and the Powered Armor Platform in District 9? How much power would it take to move them, the actual torque required from the joints,the amount of stress they place on themselves and the ground, what would they look like with current technology and its limitations, what technology would have to first be invented, etc? I know you could make an amazing episode out of each one given their vastly different scales, purposes, and the theoretical technology behind them.

Hell, maybe one day if you become popular enough and have the time branch off into the speculative realm of video games and the physics behind them and their cutscenes. :D No shortage of content there suggested by a possible fanbase that's OVER 9.8 THOUSAND!!!!!!!!!! squared.

Thanks for your great post Saulkar. The interesting thing about your request is that Colby and I both work for a robotics company for our day jobs. I do concept designs, marketing and filming, along with 3D animated simulations for robots and automation. Colby is a Senior Mechanical Engineer and he takes the designs that I work on and actually engineers the concepts and turns them into buildable designs for our assemblers.

If there's anything we may already know a bit about without having to do some extra research, it's robotics... maybe not in the vein of District 9 or Real Steel, but definitely the concepts, current technology available, and the mechanics/forces necessary to make it all happen. So look for an episode showing off our knowledge in that area later on.

Thanks very much for supporting the show!

Jason Dean
REEL PHYSICS

Please add the km/h somewhere - at least write it down, cause miles per hour is pure magic.
To make the show less static with only the movie scene going on you could make the equation appear as you talk about them, or at least wait a bit with the result a bit.
The second showing of the movie could use some digital addition like arrows showing direction of moving bodies.
I'm also starting to think that the effect of calculation would be much better if we could see what should happen - we don't need blood and gore, but a drawn test dummy breaking when hitting the pool on motorcycle would be awesome visualization of real physic.

ReelPhysics:
snip

Brilliant episode, extremely interesting!
Thank you for keeping to SI Units, that made it so much easier to follow as both a metric generation Brit and an ex-physics student!
I love your presentation, very easy to follow, if I want to I can follow along with a pencil and paper to do the maths myself (because I actually find that kind of stuff fun).

In brief, Reel Physics is fast becoming my favourite show on the escapist and I can't wait for the next episode.

Everything this guy said I agree with (except I understand mph):

Wolcik:
Please add the km/h somewhere - at least write it down, cause miles per hour is pure magic.
To make the show less static with only the movie scene going on you could make the equation appear as you talk about them, or at least wait a bit with the result a bit.
The second showing of the movie could use some digital addition like arrows showing direction of moving bodies.
I'm also starting to think that the effect of calculation would be much better if we could see what should happen - we don't need blood and gore, but a drawn test dummy breaking when hitting the pool on motorcycle would be awesome visualization of real physic.

I feel like I'm being a bit OTT with what I'd like you guys to do, what with begging for SI units last time and ripping off someone's entire post this time, but it's only because I see so much potential in this show.

Oh, and g = 9.81ms^2 ;)

ReelPhysics:
True Lies - Motorcycle Jump

Would you prefer to jump off of a building with a motorcycle or a horse?

Watch Video

Horses are squishier, increases the time over which you're velocity changes and the force you experience is less.

Anakinnnn:
snip

I'm sure you guys know XKCD, but what you do seems very similar (and not in a like "oooh, you copycats" sort of way) to the XKCD "What If" series, where the author answers crazy physics questions, like how many bullets it takes to stop a train, or how much brighter the moon would get if you shone a laser at it. Anyone who enjoys Reel Physics would certainly enjoy "What If"

That being said, I'm loving this show. It certainly makes physics relevant and I might show it to some of my physics teachers, they generally have a good sense of humour.

maxmanrules:
I'm sure you guys know XKCD, but what you do seems very similar (and not in a like "oooh, you copycats" sort of way) to the XKCD "What If" series, where the author answers crazy physics questions, like how many bullets it takes to stop a train, or how much brighter the moon would get if you shone a laser at it. Anyone who enjoys Reel Physics would certainly enjoy "What If"

It is also worth nothing that Randall Munroe comes from a robotics engineering background, as well. So, I guess, what I am trying to say is that robotics engineers are awesome. :)

Techno Squidgy:
Oh, and g = 9.81ms^2 ;)

g=9.80665 m/s2 - it's only common sense.

Please stop the laughter. It ruins the videos. Also, you guys never took into consideration the glass. That would have impaired the motorcycle's speed and seriously, dat glass! It wouldn't have been simple glass, it would have been reinforced glass or perspex to fall into safety requirements for acting as a safety barrier against drops. The terrorist wouldn't even have managed to ride off the building, he'd have been tossed over as Arnold was and become a greasy smear on the road below.

Also, as a motorcycylist, I have to commend the advanced training the terrorist seems to have as riding like that is not something any Joe-so can just do. You have to be incredibly comfortable with the weight of the bike and your skills with riding a bike to ride like that in such a small area.

I watched (and commented on and got feedback to my comment from you guys) the first episode and I'm glad to see that you guys seem to have almost perfectly adapted the show like I said and others. That means a lot, thank you. Keep up the good work, I see you guys are polishing off the rough edges and in my opinion, the quality is increasing with every episode.

Draconalis:
Suggestion:

Death Race

Specifically, how mobile those cars could actually be with all their weaponry attached, and in cases where it's known, how much slower a vehicle will be due to gun recoil.

Seconded! Death Race being a great example of a trope used elsewhere, from Mad Max to Twisted Metal.

Great show--thank you!

Since you brought up S.L. Jackson, how about looking into something a little different. In Snakes on a Plane, a man is crushed by an anaconda. How big would a snake have to be to kill--not eat, just crush--an average-size American (since the averages are different in different locales) male?

Anyway, have fun finding more examples of physics to teach (to some: it's not nitpicking, it's teaching)!

The Lugz:
snip

In a motor vehicle horsepower has 0 effect on the vehicles overall performance brake horse power does, they are two separate things. Also in motor vehicles especially motorcycles bhp or Kw of the vehicle is not the key property defining its acceleration, it has much more of an effect on the top speed. A heightened engine speed or rmp is the main property restricting acceleration followed by weight.

"because it has to either drop it's clutch or do a burnout and then rack up the rpm to get anywhere close to it's
rated power, where power is a function of engine psi/revs" I take it you have never ridden a motorcycle at high speed starting from stop?

"where power is a function of engine psi/revs" I'm sorry but that's totally gibberish are you talking hp or bhp? I'll assume you mean hp, but how on earth is the power of the engine =P/RMP ?

"whereas the horse's muscles work extremely efficiently in a high torque" Just what? are you trying to say a motorcycle does not create large amounts of torque?

I don't mean to be a dick but I do this for a living and it just disappointing to see such a fundamental lack of basic principles.

If your really interested start by reading the definitions of:
Power
Torque
Horse Power/ Brake Horse Power

and perhaps read something on the fundamental principles of ICE (Internal Combustion Engines)

Baron-connect4-von-smythe:
All we need to do is assume it's a point motorcycle in a vacuum... He'll make it no problem... Perhaps the film had mathematicians on staff instead of physicists.
Signed... A mathematician (I prefer numbers ninja)

Then everyone would suffocate including the horse and combustion would stop in the motorcycles engine though.

Reel Physics guys

Perhaps it would be worth while mentioning that the calculations are heavily idealized situations that by want of necessity through lack of information have to make numerous assumptions?

Because in this clip alone there's no account of:
-Rider bike/horse mass
-The collision with the glass
-Tyre pressures
-Engine temperature
-Age of the bike
-Aerodynamics
-Tyre & Ground frictional co-efficients

And two other points
- 0-60 acceleration is used, 0-30 acceleration will be far faster
- The bike or horse would not continue at a constant x-directional velocity across the gap

I know this is very nit picky and I could go on but when you use the word physics in a program and you don't put the word "not" in front of it you kind of open yourself up to those sort of criticisms if you don't at least state that its an idealized situation. I know you stated that one of you works in engineering so your probably more than aware its idealized and you know you would not release an investigative engineering report with out stating the limitations and assumptions of any experiments of calculations used. Again sorry to be pick but would just seem a bit wrong to have people believe this is the real physics of what would happen, rather than it's what would happen if this this and this were true or ignored.

Jedi-Hunter4:
snip

well, my general engineering knowledge of 'basic principles' has been enough to get me through an nvq in engineering and uni courses as-well as projects such as building my own steam generator and yes, i still have things to learn but who doesn't? if i'm too eclectic to understand and not up to your exacting standards then i apologize for my poor phraseology
i shall clarify my point:

a bike, rated as a '100 horsepower' may, very well be incapable of delivering 100 horsepower at a usable rpm for acceleration from standstill due to many factors but will increases in total power output to it's maximum over time by increasing the frequency of explosive pressures working in the engine

where as a horse,
by comparison could deliver all it's ( considerably less, for sure ) total power in one big push
instantly and only fades from there meaning it is built for instantaneous power and nothing else
giving it a small but in this case uniquely interesting ability to best something clearly superior for a brief moment

there are problems with this whole scenario on both sides, most notably traction but that isn't really important
as the point here is the comparative power delivery method and theory

oh, and you're completely correct about the bike i'm not adventureous enough to get on something with a track record of being that dangerous as i don't have the coordination, i'd break something.. probably myself
I have, however seen enough riders do burnouts to heat up the tire lean forward and punt the rpm's up to know that's the accepted practice for that perticular vehicle

This show seems very much like Hollywood Science which was an Open university (BBC) series from about 10 years ago (IIRC)

The Lugz:
snip

K Ill try not go ott because this is one of those freak case's we're someone calls out "what are you a doctor" and they happen to be one. Except in this case I'm well qualified but I won't pretend I hold a doctorate. I hold a University degree in Mechanical Engineering and a BEng (Hons) Motorcycle & Motorsport Engineering. I'm a Motorcycle Engineer with plans of having my own race team in a small series within a couple of years and I'm currently writing a research paper on "Computational Fluid Dynamics of a Motorcycle during cornering" as part of getting my Masters Degree in Vehicle Dynamics. So I'm fairly well versed in how a motorcycle works and operates, not perfect I have allot of experience to gain as I'm still young. I also own and a ride motorcycles myself.

I apologize if my previous post was a little condescending it just really appeared like someone who was not informed passing things off as fact which just leads to ignorance. I wouldn't act like I know anything about programming etc, as I can write code in a few select programs, but in general I know F' all.

Again no motorcycle will be rated 100 horsepower, the engine might be but the bike itself will be defined in brake horse power.

Modern motorcycles with electronic ignition and fuel injection are 3D mapped with Load, RPM and desired power output, there are a load of convoluted factors that lead to that final factor but for simplicity we will call it power.

If you know rudimentary physics you know F=Ma the bike will be under a great deal of load pulling away, as it has no acceleration from a standing start. However the engine mapping will compensate by several methods such as running the engine rich, adjusting the ignition timing for optimum performance at the given rpm. Power does play its part, but its not a "real" figure in a ICE powered motorcycle it has to be calculated from other factors. What is important is the Torque, which essentially is the turning force behind the wheel. Now neither the peak on the torque or the power curves is going to be at the idle rpm or the few 1000 rpm above during pull away, but neither will it be at the peak rpm because they are not directly proportional.

http://www.moorespeedracing.co.uk/user/FIREBLADE_RACE_GRAPH.jpg
this is a quick pic example I found on Google of a power curve. Its not the best example but you can see even at just above 2500rpm, probably the tick over the bike is producing 25bhp and if that is torque on the right hand side producing just under 50% of its maximum torque.

Now the bike in the film is probably working with a carb, which I'm not as well versed in as its out of date tech in performance engines, but it will still vary the amount of fuel available to the engine. I don't know anything about horses but I'd be willing to bet at pull away rpm that motorcycle would be producing far far more torque than the the horse and the engine be producing a greater amount of power. Muscles in some animals are frankly incredible but that's why engines for an "ideal" world with less losses are overpowered. I will concede for a fraction of a second the horse may pull away faster due to cutting out the middle man as it were having to input what you want the bike to do, but that's about it. 0-10mph 10-20mph 20-30mph timings are not used in this scenario a parallel twin with that capacity is not going to perform as well using the 0-60 as it would 0-30. For example I've got a little 125 sports bike I like mucking around on 0-50 incredibly fast for the capacity 50-65 very slow as 4th gear is crap in it.

"I have, however seen enough riders do burnouts to heat up the tire lean forward and punt the rpm's up to know that's the accepted practice for that perticular vehicle" I can assure you nobody who wants to keep their tyres in one piece will purposely do a burnout to warm it up, you will just take the tyre beyond its maximum temperature and start tearing it up. If somebody is preparing to ride at speed round corners I would even say that could be lethal. The only way I could even think of that being viable would be to have specially designed tyres to do that. No serious respected professional motorcycle race series has that.

http://www.youtube.com/watch?v=SVH74PFrn8Y moto GP race start, these are 200bhp 18,000-20,000 max rev bikes, these are as hardcore as motorcycles get, no burnouts.

Jedi-Hunter4:
Reel Physics guys
snip

Hey Jedi-Hunter4,
Thanks for your passionate feedback on the show!
In regards to your first suggestion, I believe we are implying through all of our shows that the scenarios we try to figure out are summarized heavily due to episode run times... not to mention we try to not alienate the audience so much to have people tune out. When we created the show, we decided to cover the absolute basics of the scenario and see if that would work. Obviously the technical backgrounds that Colby and I have, mean we end up sitting around talking about the hundred or so details about what would factor in to "REAAAALLLLY" seeing if it would work or not... but how far is too far in regurgitating that back to an audience? We don't want to bludgeon you guys to death with information beyond what we would consider high school level physics and math. Anyone who has the knowledge to truly get into deeper details gets to think about it on a more in-depth level for fun but that's most likely a more rare audience member such as yourself. Heck, I have already been asked in several other forums to dumb the show down even further because we might be losing people... I certainly don't want to make it even MORE complicated to understand! Ha!

As for your second point... the 0-60mph was a standard that people recognize and can relate to... we hope. That's why we chose that. Plus, we don't know the stats for the bike's acceleration in 0-30mph, but we were able to look up the specs from the manufacturer on the estimated 0-60mph.

Finally, your third point may mean you missed a lot of the finer points in the episode unless I misunderstood. The X travel was certainly not linear at all and we discuss that while talking about how they drop 100 meters in the Z while traveling in the X. In fact, I would say that's a large portion of the result. Now we don't get into the deceleration of X while simultaneously accelerating in the Z... but again, we cut that for the length of the show not to mention these details (for the most part) do not change the result. Is that what you are referring to, or did I get you wrong?

We love the math and physics enthusiasts who want to explore the finer details and it's awesome to discuss all of that, but like I mentioned earlier, it's a fine line to cover the basics and give enough information to add credibility to the show and yet still not overdose the audience on foreign concepts.

One last thing to note is the information we have to work with. In the real world, when Colby and I are creating robotics and automation designs, we have all of the technical specifications to do all of the calculations necessary to make it happen. Very little is left to our imagination. However, in movie scenes, we have to guess at almost everything which means we don't have real data. It's all assumed and guesstimated which in turn yields only enough data to make broad calculations. If we truly decided to start covering the absolute finest details, I believe our credibility would actually decrease because most of the extra data isn't known and we would be assuming all kinds of things that wouldn't be true.... such as: What is the real racing history of the horse? Is he shoed for asphalt or dirt? How much fuel is in the tank of the motorcycle? How much does Arnold and the terrorist weigh? Is the motorcycle modified in any way? What is the real surface of the rooftop? Could the horse dig into it with his hooves like a light gravel top layer over deformable tar that might act like dirt? What was the density and design of the glass so we could calculate its resistance against the motorcycle front wheel? How windy is it that far up and how much would it affect the air resistance of all of the bodies involved? How far in the X and Z was the other building (even though it doesn't really even exist)?

Sorry, I got a little long-winded here, but I hope that gives you and maybe everyone else a bit of insight into our thought process on the show and why we make the decisions we do when mapping out an episode. We love the feedback and the amount of thought that everyone is putting into the show and can't thank you all enough. We especially love the Escapist for allowing us to give it a shot!

Thanks again for supporting the show!

Jason Dean
REEL PHYSICS

Jedi-Hunter4:
snip
http://www.youtube.com/watch?v=SVH74PFrn8Y moto GP race start, these are 200bhp 18,000-20,000 max rev bikes, these are as hardcore as motorcycles get, no burnouts.

fair enough, it may be ignorance to accept what i see some people doing as fact and warming the tyres in that fashion could damage them
and i appreciate your longer post explaining context of actual mechanics behind the forces involved, i think we are largely agreeing at this point i wanted to avoid a serious in depth view of a specific scenario from the outset because whenever that happens post length tends to extend.. dramatically and it's only a web series were commenting on here

i could never hope to, and don't profess to be able to fully calculate or even understand 'Every' force involved in moving any specific machine i was simply applying general engineering logic to get a quick and dirty result
because
the exact performance of the bike at any given moment is the result of so many systems i'd be hard pressed to mention them all in a post let alone calculate for them all, as you say the engine management system alone modifies the engine well out of a basic otto cycle and makes it impossible for me to comment on what's going on in there without knowing the program, or having experience in general bike characteristics, as for example i don't know if bikes use the same turbo/inter-cooler/lsd type systems some cars do i would assume they don't but that's the point, isn't it!

the crudeness of my logic would mean my result may be similar to what would happen to a lawn mower engine
bolted to some wheels

i will, of-course defer to you in cases related to motorbikes as i have little experience in the specific field
power on, i'll happily listen and may learn things seeing as you seem to be the best qualified to explain the exactitudes

#Edit:

i recon these bikes would beat the horse ( just a little bit! )
http://www.youtube.com/watch?v=VKe74wWwteM
also, they do burnouts so it's probably people ( inproperly ) emulating these that i've seen then

Reel Physics

Thanks for the reply, I do have to say I watched the tank parachute one and really enjoyed it. Maybe I took things a little too literally.

Can I make a couple of suggestions you might find interesting?

The explosion in Independence Day in New York, just how much traditional explosives would that take to form a wall of fire in that much area?

And my other would have to be Arnold again, in commando jumping from a long way out of a plane
https://www.youtube.com/watch?v=Yk7vgOU2Ho8

cheers for your time

Jedi-Hunter4:
Reel Physics
snip
Can I make a couple of suggestions you might find interesting?

The explosion in Independence Day in New York, just how much traditional explosives would that take to form a wall of fire in that much area?

And my other would have to be Arnold again, in commando jumping from a long way out of a plane
snip

Independence Day is on our list and so is Commando. The only problem with Commando is going that far back, I feel like maybe we are going to miss the mark with the age of our audience having never heard of that movie, much less seen it. To me, it seems like yesterday, but that may also mean I am getting old. ;) However, we may try to do some of the great 80s action flicks and see what the reception is overall that might open the door to exploring 30+ year old movies regularly.
Thanks again for your feedback!

Jason Dean
REEL PHYSICS

I think this may be my favorite new show on the Escapist. Great fun, even if I can't always follow the math. Not your fault, guys, I'm just bad at math.

The Lugz:
snip

Yer apologies mate.

Tbh I have studied cars but nowhere as indepth as bikes, I do work with car engineers sometimes I'm currently working with some of them to develop a vehicle that will do 1500mpg as I mainly do fluid dynamics, IC engines and motorcycle dynamics so I'm working on doing the engine mapping for them. but yer not 100% sure on all the details of how they do things in cars.

I know you didn't ask but in case you wondered In general bikes don't utilize turbos, for cornering on bikes you need the power curve to be as smooth as possible so there's no jarring. There's also the problem that the massive increase in torque often causes the bike to wheelie. Turbo lag is also a problem as one of the key things with bikes is they are extremely responsive so turbo lag really hampers that.

Although I do know a engineer who worked on making A suzuki hayabusa for a private customer with a turbo installed in it. He said it went like crazy but where you had to be so careful on the throttle to stop it flipping or highsiding in corners it just made it hell to ride.

"the exact performance of the bike at any given moment is the result of so many systems" yer nail on the head there, so many many factors one of my undergrad works final year was creating a spreadsheet go knows how many pages long for "snap shot" scenario must of been at least 100 factors and even then had to state there were a tonne of assumptions, from assuming regular atmospheric conditions to ignoring the centripetal forces generated in the crank and the effect they would have on grip/slip. still of course did get to include counter steering, torsion generated in the chassis etc. In my experience because a motorcycle is technically perfectly balanced during lean in cornering unlike a car that experiences large amounts of roll , it makes it one of thee most complicated ground based vehicles you can analyse dynamically. But I do have to give a shout out that proper plane dynamicists designing wings etc have one of the most complicated jobs I've ever seen, on my current project I'm having to design some "winglets" an I'm having to communicate with aero engineers allot for help.

Jedi-Hunter4:

The Lugz:
snip

Yer apologies mate.

snip snip

But I do have to give a shout out that proper plane dynamicists designing wings etc have one of the most complicated jobs I've ever seen, on my current project I'm having to design some "winglets" an I'm having to communicate with aero engineers allot for help.

no need, there's plenty of bs in the world and i'll admit when i'm being less than clear
i haven't had experience in a specific topic and i was relying on inaccurate data to come to a conclusion
that is a poor scientific approach so you're right to correct me, really

it's funny you should mention winglets, i've seen a few fluid dynamic vortex shots of winglets in action, smoothing out turbulent air and massively reducing wing tip drag, i must say i agree with you there some of the design technology ( and materials used! ) involved in aeronautics gas flowing is superb, especially the shapes required to go supersonic and avoid pressure waves hitting wings and other vulnerable components that at first glance seem to be inefficient
but that's just another subject i'm no expert in!

at the moment i'm studying software development, for a ( hopeful ) future in robotics
with my basic engineering qualifications
I've already done proto-board programming using com devices, ( infrared programmable rover-bots ) and some basic tasks like line following, rpm sensing, dead reckoning but that's just so much fluff compared to proper programming like speech recognition, object tracking and image enhancement

so many years are going down the drain before i get anywhere in life, shame really but i guess life's a journey not a destination

anyway i think i've gone far off topic now, again.. so enjoy the new year and 'godspeed' to your cornering project

The Madman:
Glad to see you guys did an episode about it, although I think you missed a golden opportunity by going with the bike jump instead of, oh, I dunno, whether this is possible:

Thing is that this doesn't need to be calculated, it's not a question if a horse can jump to another building or if a car can pull a safe out of the wall, there's a specification and tests done that say how long a Harriers could do VTOL.
As it used for take off and landing, it's about 90 seconds (which is less than the scene lasts and even less than scene would last in real time) and it can be even less if the aircraft is loaded with ammo (which is the case since they use it in the movie). Problem is they heat up a lot and thus have a limited amount of water that cools them.
F-35 have better performance I think, but still wouldn't be enough.

Man...this show really makes me wish I was better at physics. And when I say "better" I mean "competent"

Thanks for watching everyone!

We do think about things like the glass, and condition of the tyres, if the ground was wet, how tired the horse is, carburated or injected, age of the bike, weight of the rider and the bike, the weight of Arnold, fuel levels, temperature/density of the air and the effect of drag while flying, the effect of the exhaust gasses ejecting from the tailpipe on the distance traveled, etc, etc.

There is enough material for each of these episodes to make a 30 minute long show when you consider ALL the factors and the research that goes into it. We try to cut down on the minutiae and hit the core of the physics going on.

I'm glad some of you like the bloopers. Jason and I have been friends for well over a decade and are capable of entertaining ourselves for hours making dumb puns and being ass-hats. What you see at the end of the episode is EXACTLY how we act in public, and despite our gleeful appearance, we actually are weeping on the inside due to self loathing. It's complicated. If it were biologically possible, I would bear Jason's child.

Sorry about the long winded reply.

Colby Dane
REEL PHYSICS

The content is sort of interesting, but the presentation is very lacking. The hosts seem uncomfortable on camera and production value is pretty limited. Also, the presentation of the information could stand to be less dry.

Draconalis:
Suggestion:

Death Race

Specifically, how mobile those cars could actually be with all their weaponry attached, and in cases where it's known, how much slower a vehicle will be due to gun recoil.

I think I can probably cover this one.

The armor
Think about hummers for a second: heavy as a cruiseliner but ride just fine. Why? Powerful engine. So I'd say it's possible, but you'd probably have to swap out the stock engine for a more beefy one. This seems pretty plausible in the movie's setting.

The bullets
Without going too deep into the physics, the one thing to remember whenever something is being fired is that the same force is exerted on the thing being fired as on the firing device. In case of a bullet this means the gun gets hit with the same amount of force as the bullet. So why does the bullet than go flying at a bazillion mph but not the gun? Because the acceleration an object gains after being hit by a certain amount of force is lower if the object is heavier. Translation: the bullet flies in one direction at a bazillion mph because it is very light. The gun will fly in the other direction (also known as recoil) but not nearly as fast because it is heavier. This is also why you're supposed to hold rifles really tightly against your body when firing. Your body and the gun will count as a single object that is even heavier than the gun and recoil will be much weaker.
Now think about a bullet being fired from a gun firmly attached to an armored car. Though the car will be hit with the same amount of force as the bullet, the car as a whole will barely recoil at all because of how heavy it is. Firing forward won't slow it down, firing backward will not speed it up, and firing sideways will not make it change direction. Not noticeably anyway.

OT: I keep missing what exactly the horse does differently. It's lighter? It has better traction? It's The One?

bliebblob:
[quote="Draconalis" post="6.396564.16220585"]Suggestion:
snip
OT: I keep missing what exactly the horse does differently. It's lighter? It has better traction? It's The One?

For the most part, it comes down to acceleration. The horse has a much higher acceleration in that short of a distance compared to the motorcycle that really has to ramp up the acceleration. So basically the horse launches from the building at a much faster velocity than the motorcycle... helping it to travel further in the X direction towards the other building.

I hope this helps.

Jason Dean
REEL PHYSICS

bliebblob:

Now think about a bullet being fired from a gun firmly attached to an armored car. Though the car will be hit with the same amount of force as the bullet, the car as a whole will barely recoil at all because of how heavy it is. Firing forward won't slow it down, firing backward will not speed it up, and firing sideways will not make it change direction. Not noticeably anyway.

The larger the gun, the greater the recoil, the faster the gun fires, the more cumulative the effect. Case in point, if a person were to fire a weapon meant to be mounted on a vehicle, they would go flying back. Now take a weapon that is meant to be mounted on a vehicle... and place that weapon on a vehicle not meant to have weapons mounted on it. There would certainly be some effect on the vehicles momentum.

I've heard of a gun that has such a strong recoil it can cause a jet to come to a standstill, which is what got my wondering about this in the first place.

bliebblob:
Snip about boolets!

This might be interesting for you? It all depends on the gun, and they've got some pretty heavy guns in that movie...
EDIT:

Draconalis:
Planes!

Same with you - xkcd is the source of all knowledge!
/EDIT

Anyway, on topic: It would be hilarious to go into the physics of 2012 (The neutrinos are mutating! xD) or Back To The Future. How much energy would a hoverboard require? Would Marty survive the end of the third film? Any apparent paradoxes?

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