05-10-2019, 12:08 AM

05-10-2019, 12:25 AM

Is your reference of units to system SI ? If so, there are seven basic units in the SI system:

(m) meter - length

(kg) kilogram - mass

(s) second -time

(K) kelvin - temperature

(A) ampere - electric current

(mol) mole - amount

(cd) candela - illumination;

but numbers? - hmm -

Best!

SlideRule

The ampere (A) is a measure of the amount of electric charge passing a point in an electric circuit per unit time. 6.241×1018 electrons, or one coulomb (C), per second constitutes one ampere.

another 1¢ and done

(m) meter - length

(kg) kilogram - mass

(s) second -time

(K) kelvin - temperature

(A) ampere - electric current

(mol) mole - amount

(cd) candela - illumination;

but numbers? - hmm -

Best!

SlideRule

The ampere (A) is a measure of the amount of electric charge passing a point in an electric circuit per unit time. 6.241×1018 electrons, or one coulomb (C), per second constitutes one ampere.

another 1¢ and done

05-10-2019, 12:31 AM

When you encounter units, like SI units, they are usually preceded by a sequence of one or more symbols, like 3 or 5 or 16 or 2.718. These are commonly called numbers. The product of a number and a unit is called a quantity, and is a real, physical thing.

Is this supposed to be a Socratic dialog or something?

Is this supposed to be a Socratic dialog or something?

05-10-2019, 07:02 PM

(05-10-2019 12:31 AM)Thomas Okken Wrote: [ -> ]When you encounter units, like SI units, they are usually preceded by a sequence of one or more symbols, like 3 or 5 or 16 or 2.718. These are commonly called numbers. The product of a number and a unit is called a quantity, and is a real, physical thing.

Yes, but how about dimensionless units such as those used for angular measurements. Are those real, physical things?

05-10-2019, 07:56 PM

I didn't say a unit is a real, physical thing. I said the product of a number and a unit is a quantity, and that is a real, physical thing. This is high school stuff where I'm from; isn't it everywhere?

05-10-2019, 08:41 PM

(05-10-2019 07:56 PM)Thomas Okken Wrote: [ -> ]I didn't say a unit is a real, physical thing. I said the product of a number and a unit is a quantity, and that is a real, physical thing. This is high school stuff where I'm from; isn't it everywhere?

Okay then, what I was trying to ask was whether, say, 1 radian is a real, physical thing?

05-10-2019, 09:41 PM

Sure. Draw two straight line segments that meet at one point, and draw them such that the angle between them is one radian. That's a physical angle of one radian right there.

05-10-2019, 11:41 PM

(05-10-2019 09:41 PM)Thomas Okken Wrote: [ -> ]Sure. Draw two straight line segments that meet at one point, and draw them such that the angle between them is one radian. That's a physical angle of one radian right there.

Or just draw a single line segment and subdivide into two segments by marking with a point somewhere on its length. The point then forms the vertex of an angle of Pi radians formed by the two new line segments.

I really miss Walter for discussions of units.

05-11-2019, 12:17 PM

(05-10-2019 09:41 PM)Thomas Okken Wrote: [ -> ]Sure. Draw two straight line segments that meet at one point, and draw them such that the angle between them is one radian. That's a physical angle of one radian right there.

But an angular displacement is just a purely numerical operation, basically a type of multiplication, so why does it need units appended to it? Similar affine transformations such as scaling do not need units.

05-11-2019, 06:11 PM

(05-10-2019 11:41 PM)burkhard Wrote: [ -> ]I really miss Walter for discussions of units.

Are we allowed to invoke his name here?

Just kidding.

Seriously, are we?

No, just kidding, seriously.

05-12-2019, 01:39 AM

(05-11-2019 12:17 PM)ijabbott Wrote: [ -> ](05-10-2019 09:41 PM)Thomas Okken Wrote: [ -> ]Sure. Draw two straight line segments that meet at one point, and draw them such that the angle between them is one radian. That's a physical angle of one radian right there.

But an angular displacement is just a purely numerical operation, basically a type of multiplication, so why does it need units appended to it? Similar affine transformations such as scaling do not need units.

Yeah, you are right. I think radians in fact are considered derived SI... in fundamental units of m/m, which cancelling out is as you say... :-)

08-08-2019, 01:53 AM

You've probably heard of the rapid melting of Greenland's ice sheet, with a record 12.5 billion tons lost on August 1st. It is estimated that 197 billion tons was lost in July, raising sea levels by 0.5mm. Scientists warn of a "self-reinforcing vicious cycle. Melting snow and ice darken the ice sheet’s surface, enabling it to absorb more heat and melt at a higher rate." See here.

There is some positive news though. Glyphosate, the active ingredient in Monsanto's Roundup weedkiller has been banned in a number of countries, with others restricting its use. See here.

There is some positive news though. Glyphosate, the active ingredient in Monsanto's Roundup weedkiller has been banned in a number of countries, with others restricting its use. See here.

08-08-2019, 06:40 AM

(08-08-2019 01:53 AM)Dan Wrote: [ -> ]You've probably heard of the rapid melting of Greenland's ice sheet, with a record 12.5 billion tons lost on August 1st. It is estimated that 197 billion tons was lost in July, raising sea levels by 0.5mm. Scientists warn of a "self-reinforcing vicious cycle. Melting snow and ice darken the ice sheet’s surface, enabling it to absorb more heat and melt at a higher rate." See here.

There is some positive news though. Glyphosate, the active ingredient in Monsanto's Roundup weedkiller has been banned in a number of countries, with others restricting its use. See here.

How many radians are in an ice sheet?

08-12-2019, 04:59 PM

(08-08-2019 06:40 AM)toml_12953 Wrote: [ -> ]How many radians are in an ice sheet?

Approximately Pi radians if it's a reasonably flat, planar ice sheet when the angle is measured over distances short enough that Earth's curvature isn't significant. Sorry, couldn't help myself. ;-)

The Radian:

I sensed some confusion in the thread about this unit of measure. The Radian isn't "unitless", it's a unit of angular measurement in its own right, just as with Degrees (with arc-Minutes and arc-Seconds) and Grads (100 Grad = 90 Deg). The Radian is derived from two lengths (which are a basic SI dimension): the radius of a circle (length #1) is circumscribed around its circumference (length #2). The end points of that radius length thus circumscribed define one Radian of angle around the circle as defined by the radii from those endpoints to the circle's center. It is the ratio of the two lengths, r/C, the "meter/meter" length units which cancel each make it "dimensionless", and therefore a scalar quantity. "Dimensionless" is not "unitless". The list of dimensionless units in the field of Physics is quite lengthy. The quantity in the set of these dimensionless units is a cardinal number (a positive integer by necessity) that's considerably greater than zero, but nevertheless countable and finite, and therefore its cardinality is a subset of the natural numbers.

Regarding the allegedly plummeting global insect population:

I've not yet read the treatise and can therefore make no judgment as to its credulity and veracity of its claims; my jury is still out. Nevertheless, since this is a calculator forum, insect population growth and shrinkage is stochastic. It should tend to follow Poisson and Exponential distributions, depending on whether one uses birth/death events per unit time, or time between birth/death events. Modeling specific population subsets of them in an HP or TI calculator (or a Casio or Sharp) shouldn't be insurmountable. The raw data, however, might need to be stored externally and distilled with some pre-processing for calculator use. I would anticipate the data sets regarding global insect populations are large.

John

08-13-2019, 07:42 PM

(08-08-2019 01:53 AM)Dan Wrote: [ -> ]There is some positive news though. Glyphosate, the active ingredient in Monsanto's Roundup weedkiller has been banned in a number of countries, with others restricting its use.

I bought Monsanto bonds when the price plummeted. Besides Monsanto another one you should blame for the melting of Greenland's ice.

Patrick

08-27-2019, 07:37 AM

(08-13-2019 07:42 PM)Pjwum Wrote: [ -> ]I bought Monsanto bonds when the price plummeted. Besides Monsanto another one you should blame for the melting of Greenland's ice.

Patrick

Monsanto have invested considerable resources to try to debunk findings that Glyphosate is carcinogenic, including paying Google to promote search results critical of a book they didn't like, see here.

Reminds me of the cigarette companies.

08-29-2019, 12:13 PM

Thanks to Monsanto paying high interest on their bonds I was able to acquire a mint HP-32E this week (10 EUR). This basic Spice model has no programming capabilities but it is predestined to study changes in insects populations of your area:

1. Standard method, only basic functions needed (but could harm insects and affect your result)

- catch a good amount of an insect species in your area, mark and release them (m)

- wait a few days for them to mix with the rest of the population

- catch a good amount of the insect species in your area (n)

- count the marked and recatched specimen (r)

- your population p is p = m*n/r

2. Read somewhere in the Internet, uses regression analysis (but could harm trees)

- count number of insects on a medium sized tree branch (i)

- count the tree branches of the tree crown

- meisure the circumference of the trunk (t)

- repeat the branch count and the trunk measurement on a good amount of trees (b)

- construct a regression model for crown size depending on trunk circumference (this relation should be in fact linear and an HP-32E will suffice, it's an awful lot of typing though)

- your population p is p = sum (all trees in your forest, i*b(t))

Cheers

1. Standard method, only basic functions needed (but could harm insects and affect your result)

- catch a good amount of an insect species in your area, mark and release them (m)

- wait a few days for them to mix with the rest of the population

- catch a good amount of the insect species in your area (n)

- count the marked and recatched specimen (r)

- your population p is p = m*n/r

2. Read somewhere in the Internet, uses regression analysis (but could harm trees)

- count number of insects on a medium sized tree branch (i)

- count the tree branches of the tree crown

- meisure the circumference of the trunk (t)

- repeat the branch count and the trunk measurement on a good amount of trees (b)

- construct a regression model for crown size depending on trunk circumference (this relation should be in fact linear and an HP-32E will suffice, it's an awful lot of typing though)

- your population p is p = sum (all trees in your forest, i*b(t))

Cheers

08-29-2019, 02:28 PM

(08-29-2019 12:13 PM)Pjwum Wrote: [ -> ]Thanks to Monsanto paying high interest on their bonds I was able to acquire a mint HP-32E this week (10 EUR).

Wish I was sharp enough to recognize the opportunity when the investment herd panics and stampedes away!

08-31-2019, 07:22 AM

(08-27-2019 07:37 AM)Dan Wrote: [ -> ]Monsanto have invested considerable resources to try to debunk findings that Glyphosate is carcinogenic, including paying Google to promote search results critical of a book they didn't like, see here.

This somewhat critical review of Carey's book is worth a read: Hogwash! A review of Whitewash by Carey Gillam.

08-31-2019, 09:56 AM

(08-31-2019 07:22 AM)ijabbott Wrote: [ -> ]This somewhat critical review of Carey's book is worth a read: Hogwash! A review of Whitewash by Carey Gillam.

Hardly. The reviewer, "Biology Fortified", is one of several "industry partners" Monsanto worked with to try to discredit the World Health Organisation before it listed glyphosate as a possible carcinogen, according to this site.

"Biology Fortified" is also linked to the "Genetic Literacy Project", which receives money from companies to "shame scientists and highlight information helpful to Monsanto and other chemical producers".

Monsanto claims glyphosate is safe to drink. That's what they said about Agent Orange too.