Unit conversions involving Pascals

  • Thread starter Thread starter chriscarson
  • Start date Start date
  • Tags Tags
    Unit
Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
Sign up Log in
67 replies · 8K views
chriscarson
Messages
197
Reaction score
26
Thread moved from a technical forum
Summary:: Pascal units digits

Do somebody have a chart that converts pascals , mega pascals etc to units to know how many digits or zeros there are after the point please ?

Thanks
 
Physics news on Phys.org
So for example when you have the result of 15 625 000 N m 2 how you put in pascals ? 15 625 kPa ?

Thanks
 
chriscarson said:
So for example when you have the result of 15 625 000 N m 2 how you put in pascals ? 15 625 kPa ?

Thanks

Yes, ##1 \text{ Pa} = 1 \text{ N} \text{m}^{-2}## by definition. Like @Vanadium 50 alluded to, the SI prefixes are general.
 
Last edited by a moderator:
  • Like
Likes   Reactions: vanhees71 and chriscarson
etotheipi said:
Yes, ##1 Pa = 1 Nm^{-2}## by definition. Like @Vanadium 50 alluded to, the SI prefixes are general.

So 1 Pa = 0.01Nm with tha little -2 ?
 
chriscarson said:
So 1 Pa = 0.01Nm with tha little -2 ?

No, ##\text{N} \text{m}^{-2}## is equivalent to ##\frac{\text{N}}{\text{m}^{2}}##! It has no relevance to the prefix whatsoever!
 
Last edited by a moderator:
  • Like
Likes   Reactions: chriscarson
etotheipi said:
No, ##Nm^{-2}## is equivalent to ##N/m^{2}##! It has no relevance to the prefix whatsoever!
Ok
Thanks . Have to study more about these to understand.
 
chriscarson said:
So for example when you have the result of 15 625 000 N m 2 how you put in pascals ? 15 625 kPa ?

Thanks

You seemed like you had it here! You can think of units sort of like algebraic quantities. To do the conversion, you could write down

##15625000 \text{ N}\text{m}^{-2} = 15625 \times 10^{3} \text{ N}\text{m}^{-2} = 15625 \text{ kN}\text{m}^{-2} = 15625 \text{ kPa}##

just like you obtained. Once you get the hang of it, you'll find that you won't really need to think at all/write all of that junk out!
 
Last edited by a moderator:
  • Like
Likes   Reactions: chriscarson
etotheipi said:
You seemed like you had it here! You can think of units sort of like algebraic quantities. To do the conversion, you could write down

##15625000 Nm^{-2} = 15625 \times 10^{3} Nm^{-2} = 15625 kNm^{-2} = 15625 kPa##

just like you obtained. Once you get the hang of it, you'll find that you won't really need to think at all/write all of that junk out!

I notice you made always a -2 on the m .
 
Mister T said:
##m^{-2}=\frac{1}{m^2}##

It s ok I give up . But thanks anyway for your help .
 
etotheipi said:
You seemed like you had it here! You can think of units sort of like algebraic quantities. To do the conversion, you could write down

##15625000 Nm^{-2} = 15625 \times 10^{3} Nm^{-2} = 15625 kNm^{-2} = 15625 kPa##

just like you obtained. Once you get the hang of it, you'll find that you won't really need to think at all/write all of that junk out!
And it's very important to typeset units in roman (upright), it should read
$$1 \, \text{Pa}=1 \, \text{N} \, \text{m}^{-2}=1 \, \frac{\text{N}}{\text{m}^2}$$
etc.
 
  • Informative
  • Like
Likes   Reactions: chriscarson and etotheipi
vanhees71 said:
And it's very important to typeset units in roman (upright), it should read
$$1 \, \text{Pa}=1 \, \text{N} \, \text{m}^{-2}=1 \, \frac{\text{N}}{\text{m}^2}$$
etc.

Ah that's useful, never knew \text{} was a thing! My latex is dreadful...
 
  • Like
Likes   Reactions: chriscarson and vanhees71
Mister T said:
##m^{-2}=\frac{1}{m^2}##
chriscarson said:
It s ok I give up . But thanks anyway for your help .
Have you never seen negative exponents used to indicate reciprocals? $$10^{-2}=\frac 1 {10^2} = \frac 1 {100}$$ $$x^{-3} = \frac 1 {x^3}$$ etc.
 
Last edited:
  • Informative
Likes   Reactions: scottdave
jtbell said:
Have you never seen negative exponents used to indicate reciprocals? $$10^{-2}=\frac 1 {10^2} = \frac 1 {100}$$ $$x^{-3} = \frac 1 {x^3}$$ etc.
No . I finished school early now I m taking a course .
 
chriscarson said:
No . I finished school early now I m taking a course .
The meaning for negative exponents follows naturally from the law of exponents:$$x^{a+b}=x^a \times x^b$$
If you have an exponent ##-a##, it then follows that:$$x^{-a} \times x^a = x^{-a+a} = x^0$$ By definition(*), ##x^0=1## so we can write: $$x^{-a} \times x^a = 1$$ If we divide through by ##x^a## that yields: $$x^{-a} = \frac{1}{x^a}$$

(*) One might quibble about the grounding definitions for exponentiation. But I like to start with the idea that an empty product yields the multiplicative identity (1) just like an empty sum yields the additive identity (0).
 
  • Wow
Likes   Reactions: chriscarson
jbriggs444 said:
The meaning for negative exponents follows naturally from the law of exponents:$$x^{a+b}=x^a \times x^b$$
If you have an exponent ##-a##, it then follows that:$$x^{-a} \times x^a = x^{-a+a} = x^0$$ By definition(*), ##x^0=1## so we can write: $$x^{-a} \times x^a = 1$$ If we divide through by ##x^a## that yields: $$x^{-a} = \frac{1}{x^a}$$

(*) One might quibble about the grounding definitions for exponentiation. But I like to start with the idea that an empty product yields the multiplicative identity (1) just like an empty sum yields the additive identity (0).
I will need a very basic lesson to understand this . I started from the middle of the subject. but thanks
 
jbriggs444 said:
You could start with Wiki. Though a textbook might be better.
I will but I m focusing on what the exams will be about and we stopped to work out stress , strain, and young modulus because it s an assistant technician course.
 
chriscarson said:
So for example when you have the result of 15 625 000 N m 2 how you put in pascals ? 15 625 kPa ?

First of all it would be 15 625 000 N/m². That's 15 625 000 Newtons of force on each square meter of area. This would be, by definition, 15 625 000 Pa. And since there are 1000 pascals in a kilopascal, it would be equivalent to 15 625 kPa.
 
  • Like
Likes   Reactions: chriscarson
this one it s ok i fully understood it
 
chriscarson said:
I will but I m focusing on what the exams will be about and we stopped to work out stress , strain, and young modulus because it s an assistant technician course.

Yes, but they will expect you to understand unit prefixes and exponents. What you are learning builds upon them. Knowledge is cumulative. If you have a gap, it will come up again and again until it's filled.
 
  • Like
Likes   Reactions: vanhees71 and chriscarson
Vanadium 50 said:
Yes, but they will expect you to understand unit prefixes and exponents. What you are learning builds upon them. Knowledge is cumulative. If you have a gap, it will come up again and again until it's filled.

Yes it s true
 
Some thing more I met and can t find the mistake is,when finding the area of a circle with 25 mm radius.
When calculating in mm the result is 1964 mm
When calculating in m the result is 0.00196375 m

When converting 0.00196375 m to mm it gives me 1.96375 m not as the first result of 1964 mm
 
chriscarson said:
Some thing more I met and can t find the mistake is,when finding the area of a circle with 25 mm radius.
When calculating in mm the result is 1964 mm
When calculating in m the result is 0.00196375 m

When converting 0.00196375 m to mm it gives me 1.96375 m not as the first result of 1964 mm
An area should be expressed using a unit of area, such as square meters or square millimeters.

The conversion factor between square millimeters and square meters is 1,000,000.
 
  • Like
Likes   Reactions: chriscarson
jbriggs444 said:
An area should be expressed using a unit of area, such as square meters or square millimeters.

The conversion factor between square millimeters and square meters is 1,000,000.

jbriggs444 said:
An area should be expressed using a unit of area, such as square meters or square millimeters.

The conversion factor between square millimeters and square meters is 1,000,000.

So it s true to have different result ?
 
chriscarson said:
So it s true to have different result ? And the 0.00196375 m squared is ok in exams ?
 
chriscarson said:
Some thing more I met and can t find the mistake is,when finding the area of a circle with 25 mm radius.
When calculating in mm the result is 1964 mm
When calculating in m the result is 0.00196375 m

Try it this way: ##\pi r^2 = \pi (0.025 \ \text{m})^2##.