Needing help understanding UNITS in math!

Ryan$

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Jan 25, 2019
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Hi guys,
I want to ask if I have an equation and I solved its elements with units "cm" and I after solving it I got x=5cm ;
my question is , if I convert the result x to meter i.e x= 5/100 ; will I get the same result(same x in meter) if I solve the equation with unit meter? if yes, then why?



thanks in advance.
 

HallsofIvy

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yes, you will. Changing the original problem from cm to m is equivalent to dividing every number by 100 and that does not change the answer to the problem just as dividing both sides of an equation does by 100 does not change the solution of the equation.
 

Dr.Peterson

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I want to ask if I have an equation and I solved its elements with units "cm" and I after solving it I got x=5cm ;
my question is , if I convert the result x to meter i.e x= 5/100 ; will I get the same result(same x in meter) if I solve the equation with unit meter? if yes, then why?
You could think of it as a change of variables. If x is the length in centimeters, and y is the length in meters, then x = 100y. You are in effect replacing x with 100y in the equation, and solving for y.

If that is not clear, try it! That's the best to ask "Can I?" or "Why can I?" questions. Solve the equation both ways, and compare. Since we don't have your equation, we can't do this for you; but it's better for you to do it anyway.
 

Ryan$

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yes, you will. Changing the original problem from cm to m is equivalent to dividing every number by 100 and that does not change the answer to the problem just as dividing both sides of an equation does by 100 does not change the solution of the equation.

May I ask over here, why we need to define at all units in math? I mean lets assume that cm is the less measurement unit then if I write 5[cm] I can't convert it more? what I'm going to explain that if I have 5[km]=5*1000[m]=5*1000*100[cm] then I can't convert more .. my question "cm" doesn't consider an amount ?! for example maybe cm is about value "10" then they stated that this value will be defined as cm ??! thanks for helping .
 

Ryan$

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You could think of it as a change of variables. If x is the length in centimeters, and y is the length in meters, then x = 100y. You are in effect replacing x with 100y in the equation, and solving for y.

If that is not clear, try it! That's the best to ask "Can I?" or "Why can I?" questions. Solve the equation both ways, and compare. Since we don't have your equation, we can't do this for you; but it's better for you to do it anyway.

thanks !

May I ask over here, why we need to define at all units in math? I mean lets assume that cm is the less measurement unit then if I write 5[cm] I can't convert it more? what I'm going to explain that if I have 5[km]=5*1000[m]=5*1000*100[cm] then I can't convert more .. my question "cm" doesn't consider an amount ?! for example maybe cm is about value "10" then they stated that this value will be defined as cm ??! thanks for helping

what I'm going to ask if I reached the least ultimate measurement unit then I can't convert it to any less units because I already reached the less ultimate unit .... so I'm asking then I can assume the that the less ultimate unit is considered as "amount" but defined as "specific label like cm" ? thanks
 

Ryan$

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I'm trying to understand if we can convert unit from unit , then if I've reached a least unit , is the least unit basically represented a number ?
 

JeffM

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I'm trying to understand if we can convert unit from unit , then if I've reached a least unit , is the least unit basically represented a number ?
6 centimeters is a length, not a number. Numbers are ideas.

Are 3 chickens numbers or birds?

2 cars will take eight people on a trip, but no numbers will take anyone on a trip.

When you convert units to a new unit, you are still dealing with units.

1 meter = 100 centimeters. Units are on both sides of the equation.
 

Ryan$

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6 centimeters is a length, not a number. Numbers are ideas.

Are 3 chickens numbers or birds?

2 cars will take eight people on a trip, but no numbers will take anyone on a trip.

When you convert units to a new unit, you are still dealing with units.

1 meter = 100 centimeters. Units are on both sides of the equation.
I'm with you that 6 centimeters is a length not a number, but if I assume that centimeters is the least ultimate measurement , then how can I convert it to numbers? I mean if I have 5 cm, then it says that the length is 5cm but what's cm? 5 is a number and how long/amount of one cm? thanks
 

Ryan$

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Maybe you guys still didn't understand me, I'm trying to say that how much/far is the least ultimate measurement measure related to area? because at the end units are about numbers/amounts...........
 

tkhunny

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Maybe you guys still didn't understand me, I'm trying to say that how much/far is the least ultimate measurement measure related to area? because at the end units are about numbers/amounts...........
1) There is no such thing as a "least ultimate measurement". Feel free to let this idea vanish into the mists.
2) 5 cm is 5 cm. If you convert it to m ==> 5 cm = 0.05 m, it's still 5 cm. It cannot be converted to a number.
3) If you COULD convert 5 cm into a number... {Incantation: Lengthus be Numberus (in a mysterious voice)}... you would be changing its very nature and there would be no going back. Frankly, I don't want you doing this with my petrol. If I put 40 litres (10.6 US Gallons) of petrol in my tank, I can drive around the city, but if you come along and turn my fuel into a number, my driving will end quite abruptly.
4) Early mathematicians spent some time hoping something like a "least ultimate measurement" existed. Alas, there never was such a discovery or invention.
5) It seems likely that we are not understanding your question. Since it seems to make no sense, what chance have we of understanding it?
6) Question: If you call a dog's tails a leg, how many legs does the dog have?
 

Subhotosh Khan

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Maybe you guys still didn't understand me, I'm trying to say that how much/far is the least ultimate measurement measure related to area? because at the end units are about numbers/amounts...........
In what subject - are you getting into these "existential" questions? Particle Physics?
 

Jomo

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Maybe you guys still didn't understand me, I'm trying to say that how much/far is the least ultimate measurement measure related to area? because at the end units are about numbers/amounts...........
No, it is not true that at the end units are about numbers/amounts. Maybe at the end units are about a number of units. Units are simply not numbers. End of discussion. I loved physics because there was a built in check to confirm that what you did was wrong or probably correct. That check was units. For example in the end you got velocity, v = 5meters/sec2 you know you made a mistake! Let units be your friend instead of just thinking they are numbers.
 

tkhunny

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No, it is not true that at the end units are about numbers/amounts. Maybe at the end units are about a number of units. Units are simply not numbers. End of discussion. I loved physics because there was a built in check to confirm that what you did was wrong or probably correct. That check was units. For example in the end you got velocity, v = 5meters/sec2 you know you made a mistake! Let units be your friend instead of just thinking they are numbers.
Indeed. Units will save you. Please don't wish them out of existence.
 

Ryan$

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I got the point behind using units, thanks guys very cooperative !!
 
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