What cheeses me off

[TheRealTMA]

Everyone knows the SI unit for weight is the elephant… “that tram weighs the same as five elephants”; “the new Range Rover weighs half an elephant”!

They also know the size for aquatic ‘acreage’ is the Sydney Harbour… “the introduction of water saving measures has reduced annual water consumption in our city by two Sydney harbours”

What’s the SI unit for going off topic?

Blue Whales as unit of weight.

Feedback: Time to standardise blue whales, red buses and Wales

The kilogram is dead, but blue whales still come in all shapes and sizes. Plus: low energy electricity, magnetic pimples, Irish UFOs and more

www.newscientist.com

 

[Pushka]

Older retired men who assume women aren't capable of managing stuff on their own.

Was waiting in the long queue for self serve when this gent behind me asked if I was paying by cash or credit. I had been watching someone just grabbing their receipt and was about to move to that check when the gent asked his question and I had to turn around to him. Of course that person had moved out before I turned back around so old gent then tells me there's an empty check out I should go to. . Geez, how have I survived 50 years of shopping without him. (don't tell me to use the operators, they were much worse then self serve for queue length )

 

[Quickstatus]

What’s the SI unit for going off topic?

OT

self serve

I've migrated from Self Serve to Scan and Go

 

[Pushka]

OT

I've migrated from Self Serve to Scan and Go

You know what? As I was standing in the queue I then decided to do scan and go while I was waiting. Next time I'll just do it first.

 

[Vic]

Thanks. But I suspect maritime and aviation industries don’t rely on Gold FM for their weather forecasts.

I reckon it's probably the other way around. Gold FM rely on BOM or maritime weather forecasts for their news reporting

SI units can be problematic.

Ill let someone work this one out

Many medicines are described in %.
On the label a 1% solution will be something like 50mg in 5mls (or 10mg/ml)
How did the % come about?.....

hey?
This is a percentage concentration in solution. Nothing to do with SI units.
Not sure of your specific example; but 5 ml of liquid (e.g. water) has a weight of 5 grams or 5000 mg. 50 mg of salt in 5000 mg of water is (50/5000) 1% salt in mixed solution.

It could be 50 lb or salt in 5000 lb of water and still be 1% concentration in solution. Although at those volumes it's probably an industrial application not medical.

I did chemistry lab work at one stage, wait until you get to making up a 5 mol solution.

 

[Quickstatus]

Scan and go
Efficient with the green/fridgeWoolies bags as they stand up - and have then alreadysitting up in trolley.
Then scan and deposit into bags. You can organise the bags so similar items go into same bag. Like veg into one bag, meat into another etc etc. frozen into another.

I hate stacking shopping bags on top of one another so when the bags are full I checkout via scan and go and return for another load.

 

[Quickstatus]

Not sure of your specific example; but 5 ml of liquid (e.g. water) has a weight of 5 grams or 5000 mg. 50 mg of salt in 5000 mg of water is (50/5000) 1% salt in mixed solution

That's the actual specific example:
1% = 50mg of ingredient(solute) in 5ml water (solvent)
The units used are actually SI units /derived SI.

Think of weight/weight
1% implies 1 part in a hundred

So
1g of a ingredient in 100g water = 1%
1000mg in 100g water = 1%
Divide by 20
50mg in 5g water =1%
As density water is 1%
50mg in 5ml water = 1%

We just memorise 1% = 10mg/ml

I've never had a student get this right ever. I didn't when I was a Med student either.

Lots of medicines are expressed this way.

 

[Quickstatus]

5 mol solution.

That would actually be expressed in Molar M (moles / L)

 

[Vic]

That would actually be expressed in Molar M (moles / L)

yep mol is to moles as g is to grams...

That's the actual specific example:
1% = 50mg of ingredient(solute) in 5ml water (solvent)
The units used are actually SI units /derived SI.

How?

well, it's actually going to be pph, ain't it?

 

[Quickstatus]

pph

The common expression is % (mg/ml) because we actually want to now how much of x is in the vial.

So if a vial is a 1% of something and the vial is 10ml, we automatically know it contains 100mg (unless you are a med student). PPH would just be unworkable

 

[TheRealTMA]

That would actually be expressed in Molar M (moles / L)

Go Avogadro!

 

[Quickstatus]

Avogadro

Avo (NA) is so important because the SI units are actually derived from one of 7 universal constants. Avo is the one universal constant which defines the mol which is the SI unit for quantity.

mol

Mol is just the quantity. A mol solution technically is Molar M

 

[RooFlyer]

These curved monitors are meant for gamers not office workers. FIne for having multiple portrait docs open, but if trying to compare spreadsheets or project schedules or powerpoint presentations then two landscape monitors side by side if much better as you see way more columns.

Yes, hate curved monitors.

Portrait and landscape x 2. Left has Explorer open almost all the time. Right is for reviewing Word/PDFs. 2 middle for working -browser/email/excel.

Avo (NA) is so important because the SI units are actually derived from one of 7 universal constants. Avo is the one universal constant which defines the mol which is the SI unit for quantity.

@TheRealTMA may have been referring to Lorenzo Romano Amedeo Carlo Avogadro, Count of Quaregna and Cerreto.

 

[Quickstatus]

[

Lorenzo Romano Amedeo Carlo Avogadro,

That's him! He was actually a lawyer but thought law was boring

He discovered Avogadro's constant.
NA

 

[VPS]

I did chemistry lab work at one stage, wait until you get to making up a 5 mol solution.

You should try teaching it to some TAFE students who didn't want to be there. I did the class as a favour for another teacher when I was doing some contract work for them. I have never forgiven her

 

[RooFlyer]

Oh, for the good old days in the chemistry lab! Gas taps easily turn-onable and Bunsen burners to hand; conc HCl and H2SO4 was in the back of the fume cabinets, copper coil in the cupboard. Magnesium ribbon was locked away, but you could usually snaffle a bit extra during class and use it afterwards. Thankfully not silly enough to fool around with the phosphorus ...

 

[cove]

I remember school chemistry like that @RooFlyer. It was fun.

 

[Pushka]

I remember school chemistry like that @RooFlyer. It was fun.

Burning asbestos mats and setting magnesium on fire. The good ole Chem lab days.

 

[Quickstatus]

None of that compares to when we discovered the school stash of metal Na. Scored afternoon detention

 

[Hvr]

Burning asbestos mats and setting magnesium on fire. The good ole Chem lab days.

Doing experiments with cigarettes, burning them through a plunger and a filter paper to see how much cough went into your lungs.

And in an all boys school, the gas in the taps wasn't the deadliest gas in the room.