how do you calculate power(s) values

K

kraz

New member
Joined
Dec 8, 2021
Messages
8
So for example, I have 3 cm2

That would be 3*10-2
but only for just one cm ? right ?
because we have cm2 , we need to put ^2 on whole thing, or just multiply it two times ? right ?

so it should be:
3*10-2*3*10-2
or
(3*10-2)2


Is this the right way ?

I always thought it, that i should just need to multiply units, but without coefficients, meaning, i do just this:
3*10-2*10-2 so it becomes by power rules:
3*10-4

But with right way it would be:
9*10-4
 
Not sure I understand your question.

How does the \(\displaystyle 10^{-2}\) come into it? Please explain so we can help.
 
Harry_the_cat said:
Not sure I understand your question.

How does the \(\displaystyle 10^{-2}\) come into it? Please explain so we can help.
Click to expand...
because cm is \(\displaystyle 10^{-2}\) , used for calculating.
(I need this for engineering, so I just calculate using \(\displaystyle 10^{-2}\) instead of cm, to get accurate answer that i can convert to other units (m, mm, nm... )

I usually, just ommit unit name, and calculate for what prefix means numerically.
 
Last edited:
kraz said:
So for example, I have 3 cm2

That would be 3*10-2
but only for just one cm ? right ?
because we have cm2 , we need to put ^2 on whole thing, or just multiply it two times ? right ?

so it should be:
3*10-2*3*10-2
or
(3*10-2)2


Is this the right way ?
Click to expand...

Since 1 cm = 10-2 m, 1 cm2 = (1 cm)2 = (10-2 m)2 = 10-4 m2.

Therefore, 3 cm2 = 3*(10-4 m2) = 3*10-4 m2.

The 3 is not raised to a power, because it is not (3 cm)2.
 
kraz said:
So for example, I have 3 cm2

That would be 3*10-2
Click to expand...

No.

3cm2 is an area. The squared within the unit of measure doesn't imply that you do anything to the quantity (the number 3) it just means that area is measured in units of some length times another length. The number would change if we convert cm2 to m2. For example, 3 cm2 also equals 0.0003m2 which also approximately equals 0.465 square inches.

A rectangle with sides 0.5cm and 6cm would have area 0.5cm * 6cm = 3cm2
 
Dr.Peterson said:
Since 1 cm = 10-2 m, 1 cm2 = (1 cm)2 = (10-2 m)2 = 10-4 m2.

Therefore, 3 cm2 = 3*(10-4 m2) = 3*10-4 m2.

The 3 is not raised to a power, because it is not (3 cm)2.
Click to expand...

So, only 1 becomes 10-4 m2, but any number in front of this, will stay the same ?

Wow :O , no wonder i got confused on this one.
 
cm2 is an abbreviation for "square centimeter"

cc and cm3 are abbreviations for "cubic centimeter"

:)
[imath]\;[/imath]
 
1st cm^2 becomes 10^-2 is completely untrue.

1st cm^2= 1cm^2 which has units, namely cm^2. On the other hand, 10^-2 = 1/100 or 0.01 which has not units. As a result cm^2 does not equal or become 10^-2, even in engineering!

Now I do agree that 1cm^2 = 10^-2 m.

Onto my next point. If you were asked to calculate 3*2^2 would you multiply 3*2 = 6 and square that value to get 36 or would you just square the 2 which gives you 4, multiply that by 3 and get 12.

Consider this point. 2^2 = 4. Then 12 = 3*4 = 3*2^2!!!

Similarly, 3*cm = 3*10-2m = (using the associate law) (3*10-2)m = .03m
 
You must log in or register to reply here.
Top