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Questions tagged [unit-of-measure]

This tag is meant for questions concerning the use of units in the measurement of a quantity.

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Conversion of a result number to a specified unit of measure

It's a very simple question, but I need to know how to convert numbers, because in several cases I ran into this topic and felt unsure about this. So for example we're counting a unit measure of time, ...
Norbert Kts's user avatar
1 vote
2 answers
44 views

What is the reason for the ratios of square units not being the same as the ratios of units [closed]

When you have a square with side length 1 yard you get an area of 1 yd$^2$. When you convert the units of this square to feet you get a square with side length 3 and therefore an area of 9 square feet....
Sam's user avatar
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15 votes
2 answers
2k views

Which distances can I run on my treadmill?

This is a real-world question, prompted by some unusual features on my treadmill and which I thus think about while running. In a sub-menu on my treadmill, I can select a distance that I want to run. ...
A. Rex's user avatar
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1 vote
1 answer
24 views

Confusion about the units of divergence

For a 3-D vector field $V = (u \hat{\textbf{i}} + v\hat{\textbf{j}} + w\hat{\textbf{k}})$: $$\nabla \cdot V\Big[\frac{m}{s}\Big] = \frac{\partial u [\frac{m}{s}]}{\partial x [m]} + \frac{\partial v[\...
Researcher R's user avatar
-1 votes
1 answer
84 views

What does area density of mm$^{-2}$ mean [closed]

I'm not being smart right now but what does an area density of this mean $$10000 \text{ mm}^{-2}$$
amnna's user avatar
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0 answers
10 views

Conversion of Abstract Units to Time in Polynomial Modeling of Snowboarder's Motion

I am currently working on a project where I model the motion of a snowboarder using a 4th-degree polynomial. The polynomial is currently defined in abstract units along the x-axis and y-axis. I have ...
Miles Jarra Gloekler's user avatar
0 votes
0 answers
38 views

Calculate Mean Annual Solid Load → Where is my error?

I have a task where I'm supposed to calculate the "mean annual solid load" in $Mt*yr^{-1}$. I am given the following equation and a table with data. There is one example, but the numbers don'...
math-question's user avatar
1 vote
1 answer
65 views

units of terms in partial derivatives

Consider: the function f is a function of u, which is a function of a and b. $$ \frac{\partial^2f}{\partial a \partial b} = \frac{\partial}{\partial b}(\frac{df}{du}\frac{\partial u}{\partial a}) $$ $$...
Wallace's user avatar
  • 13
1 vote
2 answers
214 views

Convert ln(mm^2) to linear cm^2 [closed]

I'm working on a meta-analysis of data extracted from scientific literature. One paper reported their data as $ln(mm^2)$ (see panel F in the figure below from https://doi.org/10.1007/s11258-009-9695-z)...
Rose's user avatar
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0 votes
0 answers
28 views

How should I interpret the exponent of my units? (meters raised to the power of a number in the range $0 - 1$)

In my research I'm working with river profiles. We always define a concavity index which is a number in the range from 0.2 to 0.6. That index is necessary for the calculation of another indicator ...
Vicbute's user avatar
3 votes
4 answers
211 views

Units and $ax^2L^2+bxL+c=0$ in the real world?

It seems that most math equations that come from the real world usually come with dimensions, even though those dimensions are generally ignored. I'm speaking of general dimensions, which include not ...
David Gudeman's user avatar
7 votes
2 answers
420 views

Why is it valid to treat units as variables?

I've always taken for granted the fact that units can be treated as variables in mathematical expressions. If you have an object that travels $10m$ in $2s$, you can simply divide the length by the ...
Moyen Medium's user avatar
1 vote
2 answers
55 views

How do units work for multivectors? (Clifford/Geometric algebra) [closed]

Suppose we work with $\mathcal{G}(2)$. If the units of $e_{1}$ and $e_{2}$ are of length, it makes sense that the units of $e_{12}$ would be of area. But then what are the units of scalars? And what ...
pelegs's user avatar
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0 answers
33 views

Names for equations that do and don't explicitly include units in them?

I realize the question is vague; my question is actually how to clarify it. Is there any terminology distinguishing the two types or styles of equations in these examples? Ex. 1. The following ...
Atomj's user avatar
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0 votes
2 answers
84 views

Can the units of an arbitrary differential operator be completely arbitrary on a smooth manifold?

On a smooth manifold, given any two derivative operators $\tilde{\nabla}_{a}$ and $\nabla_{a}$, there exists a connection $C^{c}_{ab}$ such that, acting on a metric tensor $g_{bc}$, we have: \begin{...
B K's user avatar
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4 votes
3 answers
265 views

Integral as area under a curve

Let $f(x)=x.$ If the units of $x$ are meters, then the area under the curve $y=f(x)$ between $x=1$m and $x=2$m is $\frac12(2\text m)^2-\frac12(1\text m)^2 = 1.5\text m^2.$ Now let $f(x)=x^2.$ Again, ...
user avatar
1 vote
1 answer
199 views

How do I convert 60mph to light years per second using scientific notation?

I tried to follow along with this units video (https://youtu.be/hQpQ0hxVNTg) and convert 60 miles per hour to light years per second. I don't get the same answer as the video does. I feel really dumb! ...
lonious's user avatar
  • 127
0 votes
1 answer
20 views

Issue Converting Between Watts and ft*lbf/s

I am solving a mechanical engineering fluids problem and I've run into a weird unit conversion issue: The density of water is $1000\ \mathrm{kg}/\mathrm{m}^3$. This is $62.43\ \mathrm{lb}/\mathrm{ft}^...
Alexander N.'s user avatar
3 votes
2 answers
418 views

Is there a formal mathematical definition of unit systems and dimensional analysis?

I know intuitively what units are and I understand how to DO dimensional analysis fine, but it occurred to me recently that I've never really considered what units or dimensions actually ARE, that is, ...
Mikayla Eckel Cifrese's user avatar
1 vote
0 answers
89 views

The usage of percentages in probability

A problem came up in a stats course I am taking. Suppose you have a population where $50\%$ of the population likes oranges and the rest hate oranges. What is the probability that a person chosen at ...
Sebastian Osorio's user avatar
1 vote
1 answer
124 views

How does curvature relate to angle measurement in hyperbolic geometry?

This question is about the relationship between curvature and angle measurement in hyperbolic geometry... Specifically, I am trying to understand the following excerpt from pp. 489-490 of Greenberg's ...
math4's user avatar
  • 199
2 votes
1 answer
664 views

What does it mean to multiply units?

In school we were taught that multiplication is "repeated addition." Of course, that idea breaks down when asked to add 4 to itself -3 times. I have the same intuition that multiplication is ...
Nova's user avatar
  • 670
1 vote
0 answers
23 views

Formula conversion with units

I'm working with the following equation: $$MU=1000\gamma k [ONPG] \delta \frac{1}{V} \frac{N_z}{N_{cells}}$$ To which I would am trying to get to the following: $$MU \times mL \times min \times 0.5=\...
Micheal Oshare's user avatar
1 vote
0 answers
72 views

How units didn't change while differentiation?

In this example, rate of change has units cm², while the original quantity, area, also has same units. I learnt that units change just like normal ratio, that is dA/dr will have same units as A/r, so ...
Purab Bajaj's user avatar
-1 votes
2 answers
327 views

Can you raise a measuring unit to the power of zero?

Say you have a cube with its volume being 27 centimeters cubed. All its dimensions are equal to 3cm, since 3x3x3 = 27 (I know it could have different values, but that isn't the focus here), and we ...
Justquestionasker's user avatar
-1 votes
1 answer
655 views

convert 100 ticks per second to milliseconds

I used sysconf(_SC_CLK_TCK) to get time resolution on my pc. I got back 100 ticks per second. How do I convert that to milliseconds? I know there 1000 milliseconds ...
user3117455's user avatar
1 vote
0 answers
94 views

What happens to units of values treated with sin, cos...?

I know what happens when I compute a square root of 9 square metres - it's just 3 metres. But what about more weird cases, like: sqrt(4m) - square root of 4 metres - is it 2 square-roots-of-metres of ...
Paweł Lis's user avatar
2 votes
1 answer
97 views

How to find the constant $L_v$ that converts the units from millimeter per hour to watts per square meter?

I am solving one problem, where the sub term contains a constant $L_v$ that converts the units of $P$ from units of millimeter per hour to watts per square meter. The following is the equation given ...
User124356's user avatar
  • 1,617
-3 votes
2 answers
61 views

Easy way to convert from one fiat to another without using a calculator

I'm trying to convert from one fiat to another without using a calculator. In my case, I was trying to convert 25 TRY to BGN. Let's assume that 1 TRY = 0.13 BGN. That means 25 TRY = 25 * 0.13 BGN = 3....
nop's user avatar
  • 173
3 votes
1 answer
99 views

Rigorously distinguishing torque from work, or, a more accurate algebraic structure for dimensional analysis

The algebraic structure underlying dimensional analysis is commonly said to be a finitely generated Abelian group, whose generating set is the set of base units (e.g. length, time, mass, charge, and ...
zwol's user avatar
  • 492
-4 votes
1 answer
42 views

How to solve this question? I tried changing velocity to m/s and also tried changing acceleration to km/h^2 but i cannot get the answer still.

A car is travelling at a velocity of $60km/h$. It then accelerates at $200m/s^2 $ for $2$ min. Calculate its final velocity? (Answer: 84km/h)
Kiki Halim's user avatar
0 votes
1 answer
25 views

Drive time calculation given speed and distance

Building a routing application and I am running into an elementary problem with my drive time calculations. I know the formula for drive time is: ...
ziggy's user avatar
  • 103
1 vote
2 answers
82 views

Can $x^{\mathrm{cm}}$ ($x$ to the power $\mathrm{cm}$) be defined?

We all know that $x \cdot \mathrm{cm}$ is "$x$ times $\mathrm{cm}$" but I was wondering about what is $x^{\mathrm{cm}}$ ($x$ to the power $\mathrm{cm}$) can be define this $x^{\mathrm{cm}}$ ...
Atlas Say Cesur's user avatar
0 votes
0 answers
59 views

What is a Segon?

This morning I asked my Alexa device what is the arctangent of 1? to which it replied: Inverse tangent of 1 is 0.0175. Now, this answer seemed rather strange to me, as I was expecting 45° or $\...
Ron Jensen's user avatar
1 vote
0 answers
41 views

Can we add, subtract, multiply, or divide each side of an equation by a unit if there are already units on both sides?

Can we add, subtract, multiply, or divide each side of an equation by a unit if there are already units on both sides? Do they just work like numbers? Example 1 $$ 12 packs \cdot 10 dollars/pack = 120 ...
vincentlin's user avatar
4 votes
1 answer
71 views

Integral Units Question

$\textbf{Question:}$ An automobile accelerates from rest at $1+3\sqrt{t}$ mph/s for $9$ s. What is its velocity after $9$ seconds? My Answer Would Be the Following: $a(t)=1+3t^{1/2}\cdot \frac{mi}{hr\...
William Garske's user avatar
0 votes
2 answers
68 views

Convert unit measures for a problem from zill book

I have some questions about a solution for a problem from Zill book "A first course in differential equations 10th edition". I attached an image with the problem PROBLEM AND SOLUTION. I have ...
Mark Martin's user avatar
0 votes
1 answer
117 views

Correct term for percentage in decimal form (repost) [duplicate]

I am looking for a precise term of the "decimal form of percentage" - f.x. 0.35 instead of 35%. It was previously discussed 6 years ago (Correct term for percentage in decimal form) and some ...
dwight_schrute_farms's user avatar
0 votes
0 answers
86 views

How to convert minutes into months, days and minutes with a high precision?

I'm want to do a time convertion, and I' facing a precision problem. I'have the time in minutes, and I want to change it into Months, days, hours, and minutes formant I've did a table in excel to ...
user2535338's user avatar
1 vote
1 answer
590 views

Is there a unit equal to 2pi radians?

We can cut up circles in whatever size chunks we choose -- we normally choose to cut them up so that the size of the angle of an entire circle is $2\pi$ or 360. Said differently, we choose units to be ...
David Lalo's user avatar
2 votes
0 answers
84 views

Is the Algebra of Physical Quantities standardized?

I'm really surprised that I can't seem to find a canonical means of representing a measurement like 1 meter in an algebra. I found George Hart's work from the 80s (...
Dylan Madisetti's user avatar
1 vote
0 answers
38 views

Doubts regarding arc length of a circle/units

how is this dimensionally correct? why does the degrees or if expressed in radians,disappear i.e. why does length of an arc have unit meters and not radian meter/ degree meter? Can someone explain it ...
doesnt exist's user avatar
2 votes
4 answers
451 views

Inches vs Inches^3

Peace to all. After gathering and calculating the measurements by volume (of a box), will the results be in regular inches or will they be in inches^3? For example, if the dimensions of the item are ...
יהודה's user avatar
0 votes
2 answers
131 views

Which measurement unit is the correct one?

For example, Speed of car = 60 km/h Speed of car in 1 hour = 60 km I know the first one is correct, but how about the second one, and why? Another example, Price of 6 bottles = 6 dollars Price of 6 ...
Remy's user avatar
  • 137
3 votes
2 answers
790 views

What are the units of an inverse matrix?

As the title suggests. For example if I have a matrix $A = \begin{pmatrix} a & b\\ c& d \end{pmatrix}$ and all elements consist of variables with units $kg$ and then I take the inverse of ...
Hendrix13's user avatar
  • 165
1 vote
0 answers
379 views

How do I convert units from per radian seconds to arcseconds per year?

I am working on calculating axial precession of a planet orbiting a star, starting by attempting to follow along with Wikipedia's article on the topic. I have gotten through most of it without much ...
Lawton's user avatar
  • 1,851
5 votes
1 answer
228 views

How can we think of the codomain (range) of a probability density function?

Let $f$ be a probability density function (PDF) with domain $D$. How do you think about the codomain (range) of $f$? I'm only able to make sense of this when considering $f$ on an interval; $\int f(x) ...
Mike Pierce's user avatar
1 vote
1 answer
656 views

Conversion from epoch time to (dd/mm/yyyy) date format

The title pretty much explains my problem. I´m given the number of seconds that have passed since the 1st of January 1970 and I have to return today´s date in (dd/mm/yyyy) format. I know how to ...
Tomas Sexenian's user avatar
2 votes
1 answer
144 views

Can time be measured in degrees?

As far as I know, minutes and seconds (units of time) are definitely somehow related to the angular conversions we study in high school math (1 degree = 60 minutes, so on and so forth). So why don't ...
Tanya's user avatar
  • 123
0 votes
0 answers
33 views

On the Interpretation of Point in Geometry

It is said that the point is 0 dimensional and essentially defines a location. Now, what is the size of the location it represents? What I mean is what is the size of the location characterized as X ...
Sathvik R.'s user avatar

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