If 2 cars are travelling in the same direction and .... - page 2

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Извините, что по-русски,- привычка:)

Решение задачи зависит от формы представления данных и порядка ее решения. Этой задаче уже исполнилось более двух тысяч лет, в Древней Греции она была сформулирована, как "Парадокс Ахилесса и черепахи".

Суть: Ахилесс догоняет черепаху, его скорость 5 метров в секунду, а скорость черепахи - 0.5 метра в секунду; расстояние между ними 5 метров.

За секунду Ахилесс добежал до того места, где только что была черепаха, но она уже успела отползти на 0.5 метра.

То-же самое повторится многократно, но Ахилесс ВСЕГДА будет отставать от черепахи и не догонит ее НИКОГДА.

имхенько, понимание сего парадокса весьма полезно для создания корректного алгоритма.

Если будет у кого желание - переведите, if you please,- я не хочу язык корежить, давно не общался по-английски:(

 
WHRoeder:
Speed of Car1, of car2, difference in speeds. I was simply trying to show how user_123 came up with the equation 10/(Va-Vb) . Slopes [y=mx+b] if you're talking lines, speed [x(t) = vt + x0] if you're talking cars. Velocity is a vector (speed plus direction) and since they are assumed to be on the same road direction is constant.

I don't follow your reasoning, in my opinion the manner you are identifying velocity with slope isn't right.

x is a distance (in miles for example), if m1 is a velocity, in miles per hour, then when you are multiplying you get square miles by hour and then you add b1, another distance in miles. You are mixing apples and oranges.

To get the right formula, which I gave above, you have to equals times. Car a run for a time Ta, Car b run for a time Tb. Ta=(10+x)/Va, Tb=x/Vb, when Car a catch up Car b, Ta=Tb. I let you resolve the equation.

However the relation with an indicator as said by SDC isn't clear to me, would be interesting to know.

 
SDC:

I want it to be 1 because it is 1.

If we say car A moves 3x faster than car b we are talking relative velocity. A relative to B.

If we say car A is moving at 90mph we are still talking relative velocity, this time car relative to the earth. Do we need to know that the earth itself is travelling at 67000 mph (relative to the sun) to know the car is moving at 90mph ? No we dont because we are considering relative velocity, not actual velocity. We consider car velocity to be 90 relative to earth velocity of 1.

You are wrong but I give up. We are off-topic for this forum and I am not a teacher. Maybe someone more patient than me can explain you why you are wrong.

Kindly, Alain.

 

You dont need mph, we are talking relative velocity, not actual velocity (if there is such a thing). Car A is travelling 3x faster than B. How fast are the cars in mph is irrelevent.

angevoyageur2013.12.03 22:33#


However the relation with an indicator as said by SDC isn't clear to me, would be interesting to know.

Two indicators. One moves up 3 times faster than the other you want to know at what price will fast one catch the slow one. Do you need mph of the indicators or do you need 1st indicator movement relative to second indicator ? 3x

 
SDC:

This is related to movement of indicators but is easy to write with cars.

Two cars travelling in the same direction car A is 10 miles behind car B, Car A is travelling 2x faster than car B. How many miles further down the road will Car A catch up with car B. The answer is 10 miles.

But if car A is travelling 3x faster the answer is 5 miles.

4X faster is a little over 3 miles (rough calculation in my head)

It looks like I should be able to use a formula to calculate that but I am not seeing it.


Блин(Russian Cybernetic Slang) (:

Speed2=2*Speed1:

Way1=Speed1*Time;

Way2=Speed2*Time;

Way2=Way1+Distance;

... continue, please...

 

Блин(Russian Cybernetic Slang) (:

we have the same slang, except English version is пара пустяков ;)

 
angevoyageur:, in my opinion the manner you are identifying velocity with slope isn't right.

x is a distance (in miles for example), if m1 is a velocity, in miles per hour,

then when you are multiplying you get square miles by hour and then you add b1, another distance in miles. You are mixing apples and oranges.

  1. Miles per hour is speed. Miles per hour going North East is a velocity. It is you that is identifying velocity as speed.
  2. The equations for slope/Intercept
    		 The equations for position/speed
    		 
    y1 = m1 x + b1
y2 = m2 x + b2
y1-y2 = (m1-m2)x + (b1-b2) = 0 // at cross
 x = (b2-b1) / (m1-m2)         // when cross
    Slope is change in y per change in x
    x1 = v1 t + x1o                  // Speed * time + initial position
x2 = v2 t + x2o
x1-x2 = (v1-v2)t + (x1o-x2o) = 0 // at cross
 t = (x1o-x2o) / (v1-v2)         // when cross 
 t = (change in positions)/ (change in position per unit time) = time
    speed is change in position per change in time
    Same equations.
  3. There is no square miles. miles per hour * hours = change in position. change in position + initial position = new position.
 
:) кусочек пирога
 
WHRoeder:
  1. Miles per hour is speed. Miles per hour going North East is a velocity. It is you that is identifying velocity as speed.
  2. The equations for slope/Intercept
    		 The equations for position/speed
    Slope is change in y per change in x speed is change in position per change in time
    Same equations.
  3. There is no square miles. miles per hour * hours = change in position. change in position + initial position = new position.
Ok my English failed. I misunderstood the word velocity.
 
angevoyageur:
Ok my English failed. I misunderstood the word velocity.

It`s not your English, it1`s your мозг. It`s OK. имхенько:)
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