General Question

flo's avatar

Why do they sometimes use liquid measuring units for solid and vice versa?

Asked by flo (13313points) April 27th, 2015

”... liters of strawberries” for solid strawberries, or ” ...pounds of water”. Why?

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41 Answers

CugelTheClueless's avatar

What you’re calling “liquid measuring units” are not that. They are measurements of volume, and what you’re calling “solid measuring units” are measurements of weight.

Mariah's avatar

What was said above, and vice versa too. Pounds are a unit of force (weight) which can apply to any material, solid or liquid.

As for volume with solids, the only thing that’s problematic is that solids will generally have rigid shapes so there will be spaces in between, so technically that liter is not just strawberry; it has some air in there too.

Brian1946's avatar

Liquids, solids, and gasses can all have weight and volume.

flo's avatar

Thank you all.

Uasal's avatar

You can measure a liter of strawberries with water displacement, and get an actual liter without air.

Mariah's avatar

^—True! If that’s what they were doing then it really is a liter, good point.

flo's avatar

I only see it once in a blue moon.
Recipes are usually solid = weight, liquid = volume.

cazzie's avatar

What most people don’t remember is that 1 cup of oil weighs different to 1 cup of water. 1 cup of rice weighs different to 1 cup of sugar. I prefer to always work in weights of grams especially when baking.

gondwanalon's avatar

Whatever rattles your cage baby! Call it what you want it doesn’t matter. A cup of gold. A liter of gold. A Cubic Centimeter of gold. A gram of gold. (etc)

cazzie's avatar

People get confused with they have cup measures and they are trying to work out how many grams of something in a cup. I know people who think a cup equals 250g. Well, it doesn’t.

The easiest thing to measure is water because that is essentially standardised. 1 cup of water will, actually, weigh 250g. But NOT one cup of flour or rice or chocolate chips and I can’t believe the people I talk to that haven’t worked that out.

It isn’t just about the shape of the solid you are measuring, it is about the density as well. Any decent cook book worth its salt (pardon the pun) will have most measures in weights of grams with the odd ‘teaspoon’ of this or ‘dessert spoon’ of that.

JLeslie's avatar

@flo In America we almost never use weight in recipes except for meats. Bake a cake and the flour, sugar, and baking powder are all in cups and spoons. Sometimes pasta is listed by weight. Things like canned goods for a recipe are by weight if the entire can will be used in the recipe. Like a can of condensed milk, or can or tomatoes, etc., but very few American kitchens have a scale. If a recipe is written for an American home cook the only expectation is she has measuriing cups and spoons.

flo's avatar

@JLeslie Come to think of it you’re right, recipes mostly use cup, teaspoon etc.,

Uasal's avatar

Yeah, I just had to use a weight to volume converter to make a ginger lemonade syrup. Apparently 3oz of fresh ginger = 5.9 tablespoons. I rounded up to six.

flo's avatar

I still don’t understand. The air between the strawberries needs to be measured? So, instead of it telling me there is x amount of strawberries it makes sense that it says that there is x plus amount?

Uasal's avatar

No. You can measure the volume of rigid objects using water displacement. It’s third grade science.

flo's avatar

Changing the subject?

CugelTheClueless's avatar

flo, a liter is 1000 cubic centimeters. Imagine a box that is 10cm on each interior edge. It would be a cube with a volume of 1000 cubic cm (10 cm high x 10 cm wide x 10cm long), i.e, it would contain a volume of 1 liter.

Now imagine packing as many strawberries into that cube as you can without squishing any. You won’t be able to fill the entire volume of the box completely with strawberries because of the irregular shapes of the strawberries. There will be little spaces left among the strawberries that will be filled with air. So even though the box has a volume of 1 liter, its contents are not 100% strawberries, strictly speaking. There is a small percentage of air in there. It’s not x plus amount, as you put it, it’s x minus amount.

On the other hand, if you use the water displacement method, you will be able to get a liter of strawberries that really is 100% strawberries.

flo's avatar

@CugelTheClueless Thanks. How much would you say, is the weight of the air in say a pound of strawberries let’s say? It is honest of them to not charge for the air though.

Response moderated (Unhelpful)
flo's avatar

@CugelTheClueless I got it, it really depends on the irregularity of whatever the items in the box are.

CugelTheClueless's avatar

The weight of the air is negligible, but I was talking about the volume in my previous post. The volume of the air is not much either. The point is that you want to know what you’re getting and get what you pay for.

How does that line in the Gospel go? As ye measure it out to others, so shall it be measured out unto you. Or something like that.

flo's avatar

@CugelTheClueless The volume yes. The thing is if said: “I bought that one because they are not charging me for the air” people would laugh and laugh at me. And they would be right.

cazzie's avatar

If you are purchasing something by it’s weight and not the volume of the packaging it comes in and comparison shop that way, then, YES, you are not being charged for the air.

Potato chips and breakfast cereals can look like huge bags or boxes, but you need to look at the grams of product inside, not the size of the pack because half of it could just be air.

I teach soapmaking. Many people don’t realise that they are buying oil by volume and not weight. A liter or ‘Fluid Ounce’ on the packaging is a measure of volume, not weight, so when they go to make a recipe, they get a shock that the ‘Fluid Ounce’ amount doesn’t actually measure that in ounces on the scale, and that 1 litre of oil does not equate to 1kg of oil, because I insist everyone use a scale and measure out ingredients in weight. It is the only way to be precis and make a safe soap.

JLeslie's avatar

@cazzie You point out another confusing thing about the system of measure America uses, we use the word ounce for both weight and liquid. Not only do we use the word for both, but how many ounces in a cup is different than how many ounces in a pound. I don’t think my husband will ever remember that there are 8 ounces in a cup and 16 ounces in a pound. I think it is because he grew up in metric and just can’t get it straight as an adult. Although, plenty if born and raised Americans probably don’t know it either.

In metric liters are liquid and grams are weight and it’s not so easily confused.

cazzie's avatar

@JLeslie another reason it makes no sense for the US to not go metric.

flo's avatar

Yes metric is so easy, it is a mystery to me why it is not used in America.

Re. the potato chips there is no confusion there because they need to put a lot of air there to keep the chips from crushed, and we just eat it no need to convert anything to anything.

Is it only by giving me the size of the product in volume that they can keep from charging me for the air?

JLeslie's avatar

@flo They aren’t charging you for air. Well, they charge in the sense that the packaging process costs money, but the chips you can figure out the price per ounce if you want to. The weight is the chips, not the air and the bag.

@cazzie Tell me about it. Even if we stick with what we use now in America I think we should add millimeters as a commonly used term rather than talk about 1/16th of an inch. I mean really, America sucks at math and then we have to constantly divide and multiply by 8,12, and 16?! It’s ridiculous.

flo's avatar

@JLeslie I know they are not charging me for air in the bag of potato chips.

JLeslie's avatar

@flo You wrote this: “Is it only by giving me the size of the product in volume that they can keep from charging me for the air?” The answer is no. Potato chips are measured by net weight. Measuring by volume is not practical for potato chips.

cazzie's avatar

They put things in bigger bags or boxes so you think you are getting more. The eyes may deceive but the numbers don’t lie. Check the nett weight.

JLeslie's avatar

Part of the reason for bigger packaging is shelf space and shipping. It would be interesting to know how much “air” is really necessary to protect a product like potato chips, and how much is just filler to make the package look bigger. Air is in quotes, because obviously what is blown into potato chip, and other bags, is not equivalent to the air we breath, or the chips would go stale in two days.

flo's avatar

@JLeslie I have that in a different paragraph though. I have to remember to use the - key I have never seen the volume of the potato chips, it is always the weight, the net weight, like everything else if fact. I was just responding to @cazzie. I was just continuing my expression of… in the whole air thing as a whole. As in I don’t know why they can’t just give weight anyway, the same way that they not charging for the weight of the container, but they are still have the content in weight not in volume.

flo's avatar

@JLeslie I understand why you thought I meant potato chips has air, it is worth charging or there is an amount of air to charge for or talk about not charging, or something like a container of strawberries etc. there is .00000….?

JLeslie's avatar

@flo You have me thoroughly confused. I don’t know what you are getting at? Why does it matter what measure is used as long as it’s accurate. Potato chips should be done by weight, it makes sense. Liquids can be done by weight or volume.

Some products are just held to tradition. Flour is by weight in the package, even though in America we measure for recipes by cup. Pound cake was a pound of flour, pound of butter, pound of sugar, etc, etc. Then we started using cup measure. Cup cakes. Then the meaning of cupcakes evolved.

Butter is sold by weight, but the sticks are marked for tablespoons and ½ cups.

Possibly, it also depends on the packaging machines and whatever is more logical for the mechanism.

You’re overthinking it. Once there is an industry standard then it makes sense to use that standard to be able to compare products. If all of a sudden a soft drink company decided to sell by weight, it would be harder to compare price per oz. If some companies stuck to that method. Plus, some drinks are denser than others, and the weight would vary inside the same size container.

flo's avatar

@JLeslie I have already posted everything I have in this thread.
Re. ” Potato chips should be done by weight, it makes sense.” Was there any debate about that?
“Liquids can be done by weight or volume.” That makes sense too now that I have learned from @cazzie and you.

There is no need to refer to the air in the container (as far as “not charging” is concerned) because it is a joke the way I see it.

JLeslie's avatar

Ok. My mistake.

flo's avatar

@JLeslie It’s miscommunication. My English.

Re your question “Why does it matter what measure is used as long as it’s accurate.” It doesn’t matter for the people who already know. But at the store when you are trying to decide to buy or not buy this or that, it is a waste of time to start converting things. Already the amount of time we’re forced to spend reading the ingredient list in everything, so much sodium, etc. ...

JLeslie's avatar

Converting what? Most items are measured the same way within it’s group. I don’t convert in the grocery store, except on the rare occasion I have a particular recipe in mind and the label doesn’t have the right measure, or uses a measure that I have to think about. Like two cups in a pint. I don’t even consider that converting, because it’s in the same measuring system, although knowing ounces is much easier for me than remembering, pint, quart, half gallon, gallon, etc.

flo's avatar

@JLeslie I hope you’re not saying everything should go according to the most knowlegable.
Edited out.

JLeslie's avatar

Again, I have no idea what you mean.

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