2 Second Rule - Calculation Help

[blunder13]

As we all know the '2 Second Rule' is an amazing teaching tool.

I need help with a simple project. How do I calculate the actual distance at different rates of speeds?

All I really need is the answers. So at 5, 10, 15, 20, 30, 40, 50, 60 & 70 mph, what is the actual following distance in meters?

Any help would be greatly appreciated

[vonhosen]

Your speed in mph x 1.5 is roughly how many feet per sec you are traveling.
1 foot = roughly 0.305m

[Quinten]

1 mph = 0.44704 meter per second
5 mph = 2.2352 meter per second

so for the above, you would have to have 4.4m between you and the car in front to pass the same point in 2seconds at 5mph

The rest is for the reader

[TooMany2cvs]

blunder13 said:

I need help with a simple project. How do I calculate the actual distance at different rates of speeds?

Any help would be greatly appreciated

Has Maths teaching in schools really been dumbed-down THIS far...?

There are 1,609 metres in a mile.
So... 30mph is 30 x 1,609 = 48,270 metres in one hour.

There are 60 seconds in one minute, and 60 minutes in one hour.
So... 60 x 60 = 3,600 seconds in one hour.
So... 48,270 / 3,600 = 13.4 metres in one second = 26.8 metres in two seconds.

[blunder13]

All a great help, thank you.

[ZedLeppelin]

Here's a different way of thinking about the 2 second rule. Roughly....

30mph = 45 ft/sec
60mph = 90ft/sec

2secs at 30mph = How many feet travelled?
2secs at 60mph = How many feet travelled?

Now just think about the answer for a moment and the next time you can, observe how closely cars are to eachother at around 30mph.

[R0G]

Use the white lines on the road - the little lane dividing ones or the long hazards ones - so each = 10 mph

I know they are 'moving' all the time whilst driving but after a few minutes it becomes easy to do

Try it

[HarryW]

It's roughly 0.45m/s per mph, so 2 secs is roughly 0.9m per mph. Applying a safety margin of +10% rounds it up to a nice and easy1m per mph for 2 secs. So 30mph is 30m 40 is 40 etc.

Yes it's over cautious, but it's not as if you can accurately judge the difference between 26m and 30m in a dynamic environment anyway...

[Pete317]

IMHO, it's very much easier to judge a 2-second gap than some distance along the road which you first have to calculate.

BTW, rough and ready way to convert mph to m/s: multiply by 4 and divide by 9

Edited by Pete317 on Friday 16th October 10:41

[TooMany2cvs]

Pete317 said:

IMHO, it's very much easier to judge a 2-second gap than some distance along the road which you first have to calculate.

Only if you can count to two. Which, going by the need to start this thread, might be a bit of an assumption.

[Pete317]

TooMany2cvs said:

Pete317 said:

IMHO, it's very much easier to judge a 2-second gap than some distance along the road which you first have to calculate.

Only if you can count to two. Which, going by the need to start this thread, might be a bit of an assumption.

If you can't count to two then you just might have a wee bit of difficulty calculating the distance, wouldn't you say?

[TooMany2cvs]

Pete317 said:

TooMany2cvs said:

Pete317 said:

IMHO, it's very much easier to judge a 2-second gap than some distance along the road which you first have to calculate.

Only if you can count to two. Which, going by the need to start this thread, might be a bit of an assumption.

If you can't count to two then you just might have a wee bit of difficulty calculating the distance, wouldn't you say?

Indeed. You might have to start a thread asking how to do it.

[ZedLeppelin]

TooMany2cvs said:

Pete317 said:

TooMany2cvs said:

Pete317 said:

IMHO, it's very much easier to judge a 2-second gap than some distance along the road which you first have to calculate.

Only if you can count to two. Which, going by the need to start this thread, might be a bit of an assumption.

If you can't count to two then you just might have a wee bit of difficulty calculating the distance, wouldn't you say?

Indeed. You might have to start a thread asking how to do it.

Patronising idiots! If someone asks a question, answer it. Who are any of you to judge and poke fun at anybody else? You are nothing more than playground bullies who pick on kids who you know won't kick your arses.

try this. The next time someone laughs in your face after you asked a question about something you needed help understanding, just remember that your looking in a mirror.

[TooMany2cvs]

ZedLeppelin said:

The next time someone laughs in your face after you asked a question about something you needed help understanding, just remember that your looking in a mirror.

If I had to ask an answer to that simple a question, I'd be laughing at myself.

[tulloch]

http://www.scilearn.com/blog/dyscalculia-number-bl...

[300bhp/ton]

blunder13 said:

As we all know the '2 Second Rule' is an amazing teaching tool.

I need help with a simple project. How do I calculate the actual distance at different rates of speeds?

All I really need is the answers. So at 5, 10, 15, 20, 30, 40, 50, 60 & 70 mph, what is the actual following distance in meters?

Any help would be greatly appreciated

Why would you want it in metres? Surely on a road in the UK yards would be more appropriate.

Edited by 300bhp/ton on Monday 19th October 14:23

[gavsdavs]

blunder13 said:

As we all know the '2 Second Rule' is an amazing teaching tool.

I need help with a simple project. How do I calculate the actual distance at different rates of speeds?

All I really need is the answers. So at 5, 10, 15, 20, 30, 40, 50, 60 & 70 mph, what is the actual following distance in meters?

Any help would be greatly appreciated

Without wanting to appear too patronising, you already have the answer, just not in the units you're after.

The speeds you quote are MILES PER HOUR.

Since you want to understand how far that is in SECONDS, you need to begin transposing the units.

You begin with the unit of MILES. Using google, find out how many yards (if that's the unit you want to know) there are in a mile, and multiply that by 5, or 10, (and so on)

You then know how many yards per hour you are travelling at X miles per hour.

Then

You want to know how far you travel in seconds, as opposed to hours. So, divide the yards you worked out in part one by 3600 (that's the number of seconds in an hour), and you have the number of yards you will travel per second, at X miles per hour. Multiply by two for 2 seconds distance.



Did you get any maths qualifications ?

[talksthetorque]

Right OP, ignore the twits above. We all have our skillsets, and I'm assuming you can drive and you know a mate who can press a button or two.

Get a paintball gun and a stopwatch. There will be one on your Samsung Galaxy.
Sit your mate on the passenger side with his arm outside the car pointing the paintball gun at the road vertically down
Drive at the steady speed you wish to know the distance for.
Get your mate to fire the gun directly at the floor, and at the same time start a stopwatch with his other hand.
When two seconds has passed as indicated by the stopwatch your mate should fire the gun at the floor again.
Stop the car, get out and measure the distance between the two paint splats ( use the centre of each splat)
Repeat for all the different speeds you want to know the distance travelled.

[waremark]

blunder13 said:

All a great help, thank you.

Far the easiest way is to say the distance covered in 2 seconds is about the same in yards as the speed in mph, so just a little less in meters:

30 yards at 30 mph
60 yards at 60 mph (accurate answer 53 meters)

etc.

While not exact this is closer than a normal person can judge distances.

When I learned to drive, rather than learning the two second rule I learned that a suitable following distance was one yard per mile an hour, ie as above.

In my many Rospa retests I have never been asked questions about this or stopping distances. I generally demonstrate enough knowledge of Roadcraft and the HWC in commentary that I don't get asked formal questions at all.

[IcedKiwi]

waremark said:

In my many Rospa retests I have never been asked questions about this or stopping distances. I generally demonstrate enough knowledge of Roadcraft and the HWC in commentary that I don't get asked formal questions at all.

On my IAM test (admittedly my only one) the test was started with HWC questions. No questions with numerical answers though, just traffic light sequence/meaning, meaning of double solids line and exemptions to cross etc.