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Unit conversion question

username1550793

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(edited 3 years ago)

Reply 1

mqb2766

Original post by tiger1296

What is the difference between NM and N/M? How does this affect the conversions.

Say I wanted to convert 50KN/M to N/M, what is the difference between this and simply 50KNM to NM?

Any help would be appreciated

If N is Newtons and M is Metres, then
NM is Newton Meters, i.e. force * distance (which is torque)
N/M is Newtons per Meter i.e. force / distance (not really sure what this is)

Reply 2

ZombieTheWolf

NM= N×M
N/M= N × 1/M

If you want to convert 50KN/M into XN/M you simply = 50 × 1000 or basically 50 × 1000/1.

If 50KNM to NM, you simply multiply 50 by 1000, because Kila means thousand.

For example, if you had 40km/h and wanted m/s, you 40 × 1000 and divide by 3600
(Please correct me if I am wrong)

(edited 5 years ago)

Reply 3

ghostwalker

Original post by tiger1296

I am not familiar with "M" in this context.

"m" is the standard SI symbol for metres. And "k" is the standard symbol for thousands.

Assuming you meant that, then

Nm is a measure of torque, and N/m could be weight per unit length or surface tension.

In either case converting kN/m to N/m, or kNm to Nm, you'd just multiply by 1000.

Reply 4

username1550793

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(edited 3 years ago)

Reply 5

username1550793

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(edited 3 years ago)

Reply 6

zp021103

Original post by tiger1296

I have tried this, but I am getting the wrong answers, here is the question:

Rank the following values of uniformly distributed load in INCREASING order of magnitude (i.e. Smallest (1) to Largest (4))
50 kN/m
0.2 N/mm
30 kN/mm
400 N/m

Convert all into N/m its so easy

Reply 7

username1550793

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(edited 3 years ago)

Reply 8

username1550793

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(edited 3 years ago)

Reply 9

zp021103

Original post by tiger1296

I've tried to do that but I keep on getting it wrong somehow, although I don't have any issues with the converting questions like Knm to nm

Rank the following values of uniformly distributed load in INCREASING order of magnitude (i.e. Smallest (1) to Largest (4))
50 kN/m Answer 1
0.2 N/mm Answer 2
30 kN/mm Answer 3
400 N/m

50 kN/m -> you wanna get rid of the K to get N/m. So you multiply by 1000.

0.2N/mm -> you wanna turn mm to m. but you're dividing by mm (it's N/mm not Nmm) so you divide by 1000 (which is same as multiplying by 1/1000)

30kN/mm -> multiply by 1000 to get rid of K. divide by 1000 again to get rid of milli.

400N/m is already in the right form.

(edited 5 years ago)

Reply 10

ZombieTheWolf

Original post by tiger1296

50KN/M = 50×1000= 5000N/M

0.2N/mm= 0.2 ÷ 1,000 ( ÷ 100 to get from m to cm, ÷ 10 to get from cm to mm) = 0.0002N/M

30KN/mm = 30 ×1000 and divide by 1000 so 30N/M

400N/M

So, 0.2N/mm
30KN/mm
400N/M
5KN/M

Although, now that I am looking at it, if there are 0.2 newtons per a mm, and there are 1000 mm in one m, then surely 0.2×1000? That gives 200N/M which would be answer 2. And If we did the same for 30KN/mm, then that would be the largest (30,000).

(edited 5 years ago)

Reply 11

ghostwalker

Original post by tiger1296

So you are saying there is no difference between writing nm and n/m?

There is a difference - they mean different things. But as far as the conversions you mentioned, the conversion factor is the same.

I have come across an exam question, where it asks for some conversions, one group has simple nmm and knm to nm, the other has Kn/m and n/mm to n/m questions that I have gotten wrong twice now, which is confusing me as i'm doing the same thing as before, but now I feel there is something different about it

Don't know what nmm is. My best guess is Nmm, for Newton millimetres (a rather weird unit). In which case to convert ot Nm (please get the cases right - it is important), would require dividing by 1000.

Converting kNm to Nm is multiply by 1000.

Converting kN/m to N/m again multiply by 1000.

Converting N/mm to N/m multiply by 1000.

Reply 12

ghostwalker

Original post by tiger1296

The "M" is metres, I just capitalised it for some reason

Anyway, here is the question I keep getting wrong

Rank the following values of uniformly distributed load in INCREASING order of magnitude (i.e. Smallest (1) to Largest (4))
50 kN/m Answer 1
0.2 N/mm Answer 2
30 kN/mm Answer 3
400 N/m

So, we convert everything to the same units.

50kN/m is 50000 N/m which is 50 N/mm.
0.2 N/mm stays as is.
30 kN/mm becomes 30000 N/mm
400 N/m becomes 0.4 N/mm

Reply 13

username1550793

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(edited 3 years ago)

Reply 14

ZombieTheWolf

Original post by tiger1296

I just tried the orignial order you gave and the only one in the right place was the 0.2n/mm, the rest were incorrect

I'm so bad at maths *sob* basically,
50KN/M ×1000= 5000N/M
0.2N/M ×1000= 200N/M
30KN/mm ×1000×1000 = 30 million newtons per m
400N/M

Just to correct myself, the reason I was wrong was because of when I was converting from mm to m. If we are trying to get from a value larger than m, like km, it would be ÷ 1000, but if we are getting from a value smaller than m we ÷ 0.001.

So the method is still working. Just switch 1/1000, to 1/ 0.001. Hope that helps, apologies for the mix up.