Ticket, Acceleration, Distance Covered Question | GTAMotorcycle.com

Ticket, Acceleration, Distance Covered Question

deadbanana0717

Well-known member
Hello All,...

Say a motorcycle accelerates from 0-100 in 3.4 seconds.

is there any way to calculate the distance traveled to reach 100km/h?

1) Gradual Roll on, Shift at 6K rpm on a 1999 R6. 600cc's.


2) Aggressive Roll on shifting at 9-10K Rpm on a 1999 R6. 600cc's.

Thanks
 
There are two ways of answering this question. One is to actually do it and measure; the other way requires one to know every variable including: power band specifics, time to shift, rider's mass, wind if any, grade if any, tires in use, etc. Remember that even though you know it's 3.4s, we're looking at _non-uniform_ acceleration here, which is a different thing than uniform acceleration. There are way too many variables to figure this out on paper in my not-so-humble opinion. Good luck anyhow!

EDIT: average speed is also unknown, which complicates it further.
 
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You would have to know how you got to the 100KMH.

If you assume straight line acceleration i.e. constantly increasing speed, your average speed would be 50kmh for 3.4 seconds.

50kmh is 1000(50/60/60) = 1.39 metres/second (EDIT should be 13.9 metres/second to get same answer as below post #4.)

So you would travel 3.4*1.39= 6.56 metres in 3.4 seconds - which seems a really short distance (unless I've botched this)!
But there's no way it's a constantly increasing speed, so that's wrong in real life.
 
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Basic kinematic equation: d= (v(i)+v(f))/2 X t

Assuming constant acceleration, initial velocity v(i)=0, final velocity v(f)=27.8 m/s, t=3.4s, the distance is about 47m. The velocity has to be in m/s 100km/h=27.8m/s



Hello All,...

Say a motorcycle accelerates from 0-100 in 3.4 seconds.

is there any way to calculate the distance traveled to reach 100km/h?

1) Gradual Roll on, Shift at 6K rpm on a 1999 R6. 600cc's.


2) Aggressive Roll on shifting at 9-10K Rpm on a 1999 R6. 600cc's.

Thanks
 
Hello All,...

Say a motorcycle accelerates from 0-100 in 3.4 seconds.

is there any way to calculate the distance traveled to reach 100km/h?

1) Gradual Roll on, Shift at 6K rpm on a 1999 R6. 600cc's.


2) Aggressive Roll on shifting at 9-10K Rpm on a 1999 R6. 600cc's.

Thanks

To make this situation more obvious in our heads, consider two bikes (nothing technical or realistic follows):

One bike spends 3.3 seconds slow-riding, and then, in the remaining 0.1 s guns it up to 100 km/h (impossible :( )
- That would be quite a short distance indeed

The second bike guns it up to 99 km/h in 0.1 seconds and then spends the remaining 3.3 seconds getting that last 1 km/h for the even 100 km/h
- That would cover the first bikes distance in little over 0.1 s, and be a much longer total distance.
 
There is probably a function for describing it that incorporates force (kw) on the mass of the bike and rider (~400kg) x some coefficient for drag and momentum (p) for values less than t=3.4s and s=27.7m/s.

You could use this to infer the instantaneous acceleration at a given point, but your calculated inference vs. the observed inference of the speed gun will probably lose.

If you were caught by the pacing method on a curve, it is arguable that your line shaved almost a second off the ramp which would explain why it seemed like you were going faster, but on a straight line, you are probably owned.
 
Basic kinematic equation: d= (v(i)+v(f))/2 X t

Assuming constant acceleration, initial velocity v(i)=0, final velocity v(f)=27.8 m/s, t=3.4s, the distance is about 47m. The velocity has to be in m/s 100km/h=27.8m/s
Epic first post, especially having an account for 3 years!! :)

tulipwhale


Join Date: Sep 2009
Location:Burlington, ON
Posts:1

-Jamie M.
 
WARNING: Extreme nerdiness occurring late on a Saturday night. Proceed at own risk.


I would do it in 3 phases, knowing your horse power at the 3 phases of your acceleration is easier than trying to integrate the power curve throughout (although it is possible with software).

I'd find your power in phase one, use that to determine your acceleration assume no drag at low speeds.

power in phase two, determine your kinetic friction, assume no air drag

power in in phase three, assume same kinetic friction, determine your air drag D=1/2(sigma =1)(rho @SL)(Surface area of your bike)(100 kph*1000/3600*3 (need it in ft/s))^2 or we could just assume that it's a factor of your power and say 0.15x your acceleration force which would be reasonable at those speeds.

Then you convert your power in all phases to a consistent accelerative force "pushing" you during those three phases and voila, you have your answer. Except...

If I were to simplify the question I'd say a block is accelerated in 3 phases, determine the distance covered. It spends 1s accelerated in the first phase, 1s accelerated in the second phase, 1.4s accelerated in the last phase. It's accelerative force is the average power in each phase/the velocity in each phase. We have average power, what we don't have is average velocity. there are 4 velocities, v1=0 when the block starts, v2 = ? at end of first phase v3 = ? . This obviously isn't going to work

I think at this point it needs to become a work energy problem. You know the power and the time it was applied for, so you have the energy expended in each phase. you could then determine your speed from energy for V2 because I assumed no drag at low speeds. Finding V3 we have an initial velocity (kinetic energy) plus potential energy (from the fuel burned, or the average power in phase 2 X the time it was applied for), we can determine the energy lost due to friction, to simplify we'll say it was 20% due to things like heat and friction, and we'll get a V3. and we know V4. So now we have velocities and times they were going at those speeds over an average. The three phase system might not be a perfect representation but oh well. I'll check my answer and see where I end up.

SOOOO, doing the math getting my values from: http://www.motorcycle-usa.com/69331...o/2011-Yamaha-YZF-R6-Supersport-Shootout.aspx

I'd say 25 HP in phase 1, 50 HP in phase 2 and 95 HP in phase 3. That's ideal so the distance covered that I calculate will of course be ideal. 25 HP = 18.6KW = 18.6 KJ, 50 HP = 37.2 KW = 37.2 KJ, 95 HP = 70.2KW applied for 1.4 seconds so = 98.28 KW.

V2 = (18600/(1/2*250kg))^0.5 = 12.19m/s
V3 = ((18600 + 0.8*37200)/(0.5*250))^0.5= 19.66m/s
v4 (to check) = 18600 +0.8*(37200+98.28) = 31.8m/s (114 km/h, like I said, ideal situation. Not too bad I must say though given the amount of assumptions I made, using 27.8m/s)

Average distance covered in phase 1 = 6m
Average distance covered in phase 2 = 15.88m
Average distance covered in phase 3 = 33.22m


Total around 55 m, which I would say is a reasonable number. If I was doing it in real world scenarios, I'd have to take some more distance off at the end of those 3.4s due to rider error as well as tire slip etc. Also, this was based on the 3.4s time given. If I didn't have that time, I'd have done it differently, but then there was no guarantee that you'd be at 100kph at the end. All in all, I'd say this approximates it well enough.
 
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lu smart cookies...
2 years out of engineering school and i dont even wanna read through the equations lol
 
I don't really get this thread. Is it just an academic question or were you ticketed and now trying to prove that you weren't going as fast as the officer claims?

If it's the latter, wouldn't you be more interested in the speed required to traverse distance Y in X amount of time? Or do you not know the distance and, therefore, trying to reverse engineer the scenario? I don't see how this can work to your advantage unless you know the exact distance and times the officer used to clock you (disclosure?).
 
This thread is stupid.

The theoretical minimum distance covered to reach 100km/hr is a geometry problem not a work energy problem.

The terms like 'gradual roll on' introduce too much ambiguity into the problem to possibly determine such a distance.

Sent from my HTC Desire using Tapatalk 2
 
WARNING: Extreme nerdiness occurring late on a Saturday night. Proceed at own risk.

...
...

Average distance covered in phase 1 = 6m
Average distance covered in phase 2 = 15.88m
Average distance covered in phase 3 = 33.22m


Total around 55 m...

I see! Wow that is surprisingly short. :D

I don't really get this thread. Is it just an academic question or were you ticketed and now trying to prove that you weren't going as fast as the officer claims?

If it's the latter, wouldn't you be more interested in the speed required to traverse distance Y in X amount of time? Or do you not know the distance and, therefore, trying to reverse engineer the scenario? I don't see how this can work to your advantage unless you know the exact distance and times the officer used to clock you (disclosure?).

I kinda looked at the distance on google maps :S ... approximate.

Yep! this is gonna be an ugly one... I doubt I was going nearly as fast as the cop was saying. After riding the same bike for a few years, you'd think I have a fair idea of what each gear is capable of...
 
The theoretical minimum distance covered to reach 100km/hr is a geometry problem not a work energy problem.
Actually it's a calculus problem, but either way there's no solution possible without knowing more.

Without writing anything on paper, I suspect the correct answer can be any value inside interval [0, 94.(4)] meters.
 

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