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Discussion Starter #1
I want to find out the statistics for how long it takes a murano to go from 0 to around 50mph. Does anyone know how or where to find this information? Thanks.
 

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Discussion Starter #3
Why 0-50?

Well, I got a speeding ticket pulling out of my condo complex last Friday.. they said I was going 50mph.. and the distance was less than 0.2 miles... I am trying to figure out if I can use some math in court to get out of my ticket!! I really don't think I was going 50.. but you know the Murano.. you step on the gas and it just goes.. I'm sorry officer!

Thanks for your help.
 

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It is going to be tough. If you were driving at a constant 50mph, it would take you 14.4 seconds to cover .2 miles. You will need to know how many seconds after you left the parking lot you were stopped. Then you can accurately calculate your speed. But I tell you, it will be darn close...;)
 

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Physics to the rescue!

Uh oh! Time to bust out the high school physics!

The wonderful Kinematic Equations will let us figure out how fast the Murano can accelerate (assuming constant acceleration) with the equation Vf = Vi + a*t. Using the fastest possible acceleration (0-60 mph in 7.5 sec), according to Car & Driver) we can solve for a and find that it's 0.00222 miles/sec^2.

Now to figure out how much time it would take to get to 50 MPH (0.01388 miles/second), just divide the speed by the acceleration to get 6.25 seconds.

Then to see the distance traveled when going from 0 to 50 in 6.25 seconds, use the formula d = (Vi + Vf)/2 * t to get 0.0434 miles.

Instead of the last two steps, we could plug directly into d = (Vf^2 - Vi^2)/(2*a) => (0.01388^2)/(2*0.00222) = 0.0434 miles, just to verify our answer.

So, unfortunately, it is physically possible for you to achieve what the cop says you did. As a reality check, consider that the quoted quarter mile time for the Murano is 15.9 seconds at 87 mph (thanks again to Car & Driver).
 

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Haha - something I can actually use physics for.

Nice work.
 

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GMTURBO43 said:
Haha - something I can actually use physics for.

Nice work.
Physics and mathematics are something i use all the time. You cannot argue with them! Though I also use statistics and I can say the following - you give me the value you want to get I will arrive there, with a proof!
 

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It would be tough to argue such detailed distance/speed calculations in court since many courts take even a crooked cop's word in court as expert testimony. Unless you can prove beyond a reasonably doubt that you were ticketed unfairly, the judge will always throw the book at you.

Might want to try to get your ticket amended to a non moving violation if possible.
 

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Discussion Starter #9
DARN!

Wait -

So I can't just use Distance = Rate x Time


0.2 miles = rate x 0.0017 hours

(6.25 seconds to go from 0 to 50- according to the previous calculations)

Rate = 117.6 miles/hour

So, wouldn't that be almost impossible?
 

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Re: DARN!

Mevi88 said:
Wait -
So I can't just use Distance = Rate x Time
0.2 miles = rate x 0.0017 hours
(6.25 seconds to go from 0 to 50- according to the previous calculations)
Rate = 117.6 miles/hour
So, wouldn't that be almost impossible?
No you can not!

You can use the rate * time if you are already travelling at a 'constant' rate. If you use this formula, the math naturally will show that that you are ticketed unfairly. But it is the inccorect formula to start with. ;)

The Distance = rate x time does not take into account acceleration (hence the "a" in the above equations from CP-Mike). Amazing what the "a" can do to multiply your speed :4:
From CP-mike very analytical calc, it shows that it is possible to be in 50mph in 0.2 miles for murano.

If you are still trying to pursue the use of 'math' in court, consider this: as an alternative to CP-mike equations, try to factor in the mass of a murano and wind resistance. The basic assumption of kinematic equations (above) is that every moving entities are small-mass (no mass) particle. Your murano is not; it has lots of mass and there are wind drag resistance.

So, to properly analyze the acceleration speed, you need to run the calc using the concept of :

1. Conservation of Mechanical Energy.
http://physics.bgsu.edu/~stoner/p201/energy/sld001.htm

2. Drag force of murano (drag coeeficient). The you need to plug this into the conservation of energy calc.

Anyone want to try the math? :2:
 

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Re: Why 0-50?

Mevi88 said:
Well, I got a speeding ticket pulling out of my condo complex last Friday.. they said I was going 50mph.. and the distance was less than 0.2 miles... I am trying to figure out if I can use some math in court to get out of my ticket!! I really don't think I was going 50.. but you know the Murano.. you step on the gas and it just goes.. I'm sorry officer!

Thanks for your help.
How about getting in the MO, reset the trip hit the gas and see how fast you are when you hit .2 miles? Just a thought.

I would suspect the results would be amazingly accurate. Just don't do it while the cop is there... he will give you another gift. :4:
 

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Discussion Starter #12
Gonzo - I did try that on some back roads.. I went to 50 in 0.3 miles! So, I still think the cop didn't really clock me going at 50, maybe a little under.... but they told me they only pull people over going 15 over the speed limit. And they wouldn't show me the speed clocked on the radar! I hate cops!

I did take into account the acceleration (a).. the 6.25 seconds was the time with a mutiplied in according to CP-Mike's calculations. I just used the distance and time (with acceleration) and got the rate.. of MPH.

I know this isn't right.. but would the court know any better?
 

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I will again caution you in trying to use mathematical formulas as a defense for speeding. Most of the time, the judge will just point his/her nose up the air and not even pay attention to the numbers you present. Even if the officer made up a number, the judge will still conclude that if you were not going 50, then maybe you were going 45, and thats still speeding, and you'll still get hit with a fine (and points on your driving record). I write this because I had it happen to me - I challenged a ticket because I thought I had an easy case - the officer's testimony said he turned on his radar from the opposing lane of traffic, 25 feet from my car. That would certainly not have been enough time to lock on (I would have gone by him in a fraction of a second, even at the limit). So I presented my calculations, and even presented evidence that the road was not marked with speed limit signs. Judge concluded I was using "approximations to discredit the officer and confuse the court." You can guess the outcome from there.

Its best to try to settle the case before it gets to court, by either using a traffic school option (usually you can go to traffic once to get it removed from your record), or having an attorney amend your ticket to a non moving violation (aka tail lights were out, or something similar) for a fee. In either case you'll pay a fine, but most importantly it won't go on your driving record.
 

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Here is what I would do... in a 55 MPH zone I would run 5 times going from 0-50 and timing it with another person. Put that into a spreadsheet (or other table like program).

Do this with the pedal full to the floor and then do another 5 driving as you "would normally".

Have the witness sign something "I John Smith witness these efforts to capture car performance in an effort to bla bla bla bla" and perhaps have that person come with you to court. They will never ask them anything but just the fact of having them there says something. Then just present the raw data. No calcualtions just plain data.

If under normal acceleration and hard acceleration you can't make 50 MPH in .2 miles and the fact the the officer did not present the radar gun read out to you then IMHO you would be fine. You should also present pictures and a map of where you left to where you got pulled over to prove the .2 miles distance.

If you don't have a record for speeding I can't see how you could loose.

Best of luck and keep us posted. I'm curious.

Rule of thumb... as soon as you seen the blues.... the first thing is to look at the speedo. If you were in fact doing 50 then you just have to bit the bullet... if not then fit for what is right.
 

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Police here don't have to show you the reading, and won't. Also, I've been told it's easy to fake a reading, so seeing it wouldn't matter anyway.

Once when I was young I went to court to see what it was like. There was someone trying to get out of a 200km/h in a 80km/h zone speeding ticket (~$1140 plus whatever the judge wanted to add since it was greater than 50 over). OUCH!!! His defense was that the officer didn't state explicitely that he tested the radar gun within 15 minutes after the reading was taken. The rules here are that the officer must test the gun at the start of a shift and within 15 minutes of each reading.
The ticket was not changed.
 

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More Physics

Okay, so if you are having trouble believing the 0.04-miles-to-get-to-50 figure, consider this.

We can solve for the acceleration necessary to get to 50 mph in 0.2 miles by rewriting the equation to a = (Vf^2 - Vi^2)/(2*d) and plugging in 50 mph (0.01388 mi/sec) for Vf, 0 for Vi, and 0.2 mi for d. The result is that a = 5.36x10^-4 mi/sec^2.

Now take that and plug into Vf = Vi + a*t and solve for t, the maximum amount of time you can take to get to 50 mph in 0.2 miles. This comes out to be 25.9 seconds.

Now this test is a lot easier: Can you get your MO up to 50 mph in 25 seconds? I think if you were actually trying and still unable to do that, you must have some very serious issues... 25 seconds is a long time.
 

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Re: More Physics

CP-Mike said:
Okay, so if you are having trouble believing the 0.04-miles-to-get-to-50 figure, consider this.

We can solve for the acceleration necessary to get to 50 mph in 0.2 miles by rewriting the equation to a = (Vf^2 - Vi^2)/(2*d) and plugging in 50 mph (0.01388 mi/sec) for Vf, 0 for Vi, and 0.2 mi for d. The result is that a = 5.36x10^-4 mi/sec^2.

Now take that and plug into Vf = Vi + a*t and solve for t, the maximum amount of time you can take to get to 50 mph in 0.2 miles. This comes out to be 25.9 seconds.

Now this test is a lot easier: Can you get your MO up to 50 mph in 25 seconds? I think if you were actually trying and still unable to do that, you must have some very serious issues... 25 seconds is a long time.
Well put. Even without those calculations, its easy to figure out that if the Murano can do the quarter mile in [email protected], it can definitely get up to 50 in .2 miles.
 

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Discussion Starter #18
Ok

Okay well thanks for all your help. I guess I will just hope I get a good lawyer who can at least get me no points and a judge who will be nice and make me pay a low fee!

Any other suggestions?
 
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