"Hmotnost tří litrů vody známe."

Translation:We know the mass of three liters of water.

January 21, 2018

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How am I supposed to know that you want mass instead of weight here?


Hard to say, what should be accepted, but "hmotnost" is the official name of the physical quantity (with kg as one of the basic units of the SI system), "váha" is colloquial. The same holds for "mass" and "weight".


I asked a native, he said the word order is wrong if it's just this sentence alone.


In Czech, this arrangement is possible, but it's as if Yoda said it. :D Better is: "Známe hmotnost tří litrů vody."


That is the neutral word order. Not a better order in any objective sense.


I thought you would have accusative litry after tří and genitive litrů after pět and above?


It's "hmotnost" that is in accusative. "litrů" is genitive and as is "tří" because it's "of three liters" - it described the mass. It would be the same for higher numbers: "hmotnost pěti litrů". Both words need to be in genitive.

What you say would work if we remove the "mass": "Znám tři litry vody" - "tři and litry" in accusative, but "Znám pět litrů vody" - "pět" in accusative and "litrů" in genitive. But "I know three liters of water" doesn't make much sense.


in diction. for word mass i have "hmota" "vrstva" "hromada" ?? is it equivalent of "hmotnost" ? or is it used only for physics ? thanks


The English word "mass" means many things.

"Hmotnost" is a physics term, it normally means "weight", but the proper English physics term is "mass". "We know the weight of three liters of water." is accepted. In casual language, we use the word "váha" for "weight" (and also for "scales" - the device that measures weight)

"hmota" is "(physical) matter", which can also be called "mass" in English.

"mass" is also a large group/amount, is which case it's "hromada", and the adjective "mass" is "hromadný"-

"mass" is also a religious service, then the Czech word is "mše".

Not sure why your dictionary lists "vrstva" - that's "layer" and I don't see a connection with "mass".


thank you so much!! dekuji mockrat !!


"We know the weight of three liters of water." That makes more sense. Never heard of anyone wanting to know the mass of water unles you are a scientist so what do we want here mass of weight? This is what I understand mass to be. I got this from the internet

( The most important thing to understand before you try to calculate the weight of water is the difference between mass and weight. The mass of a substance is a measure of how much matter is present, and it’s measured in kilograms or pounds. Most of the time, this is the most useful measure when you want to see how much of a substance is present. https://sciencing.com/calculate-weight-water-5118229.html


Do you think it is strange to be a scientist? Me being one I encounter the "mass" word MUCH more often. Speaking about the mass of some volume of some fluid sounds completely natural and pretty basic. Suitable for elementary school, no rocket science.

Speaking about weights only complicates everything since you have to consider the buoyancy and the density of the surrounding air and what not.

The article you quoted continues like this:

"The weight of a substance or an object is the force that gravity exerts on it due to its mass. For this reason, weight is technically measured in newtons or pounds-force. When most people say “weight” in real life, they are actually referring to the mass of the substance, because in colloquial language the words are basically interchangeable. However, in physics they have very specific meanings, and as such, you have to be careful to ensure you’re using the right words and calculating the right quantities."


ok I get your point, you being a scientist, I am just a normal person trying to learn Czech because the country and its people interest me. and since my coworkers are mainy Czechs I have the opportunity to talk to them a little . I would use weight in our very unscientific conversation .. I think not unlike others who are also trying to learn Czech so it is good that 'weight' is also accepted.


In English, "weight" is what a layman/non-scientist would use instead of "mass". In Czech, you can do the same and replace "hmotnost" with "váha". But even very common Czech people know the word "hmotnost", it's written on all packaged goods.

A very common way of rephrasing the sentence in this exercise would be: "Víme, kolik váží tři litry vody" - note the word "vážit" means to "weigh", you have already learned its reflexive variant "važit si", which means to "respect".


Thank you for the clarification. I think of mass and weight as different things (weight as a vector force, mass as a scalar unit of matter)

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