In physics there is a distinction between mass ("massa"?) and weight ("peso"?). In outer space an object still has mass, but not weight (weight is due to the earth´s gravity). Both are measured in kilograms and most people are not aware of the difference (and why should they care). As this is a language course not a science course Duolingo should use ordinary words and avoid issues like this.

If you are a physics professor vacationing in Rio, this sentence is critical to your ability to have a good time.

This is a bizarre sentence... native portuguese speakers: would you ever construct a sentence like this?

Man I thought it meant like a phrase like that car is worth some dough! somewhat but it sounds weird

I am in the science section. This sentence is totally correct in this context.

More like "why do I need to know the mass of this car".

Its far more colloquial in English to use "weight". Although yes, there is a technical difference.

In my Oxford Portuguese-English dictionary the word for weight is given as Peso.