# Did Mass Have Different Units During the Scientific Revolution?

• Chombo
In summary, Chombo is proposing a new physical quantity called lightness which would be different than mass and would be based off of force rather than kilograms. This would lead to different units for force and could potentially lead to deeper changes in physics.
Chombo
This may be a weird question, but oh well. Way back during the Scientific Revolution it would have been possible to define mass as acceleration divided by force right? Then you'd have F = a/m, and the units for force would be different than they are now.

Welcome to PF, Chombo.
You can define things any way that you want to, and use any units that you want to. Reality will remain real. The trick is to make sure that everyone is speaking the same language.
And incidentally, the 'Scientific Revolution' never officially began or ended. It goes on constantly. Perhaps you mean the Industrial Revolution'?

Last edited:
Thanks for the reply Danger, that cleared things up a bit. By 'Scientific Revolution' I meant the period of time when Galileo and others began to reject Aristotle's medieval view of the universe (i.e. the sixteenth and seventeenth centuries).

Chombo said:
This may be a weird question, but oh well. Way back during the Scientific Revolution it would have been possible to define mass as acceleration divided by force right? Then you'd have F = a/m, and the units for force would be different than they are now.

It's actually a good idea. Does it mean, mass is generated after a force gives you an acceleration? It will also mean, massless particles can accelerate whenever they 'wish' without force -- this is violation to 1st law... so it's a nice question to probe.

Explanation:

m = F/a. (definition)

So when there's no force, mass = 0/a = 0, provided a != 0 .. Particles, if they have acceleration without force, they are massless, so if we find a massless particle, it can actually violate first law.

If F = 0, a = 0, m=0/0 , means undefined. therefore, for mass to appear as something real, there must be first force, and resultant (?) acceleration.

Yet another point. Mass've been the key between force and acceleration. Since mass is now an 'aftereffect' of F and a, what's the key between them?

Your question is very interesting to think.
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Chombo said:
(i.e. the sixteenth and seventeenth centuries).

Ahhh... that would be part of what we generally refer to in the western world as the 'Renaissance'. It spanned roughly the 14th - 17th centuries. While predominantly associated with art, it also saw large upsets in the field of science.

But, that's not really a definition; it's a statement of what can be experimentally observed. F = a/m leads to the extreme conclusion that one could move very large masses with a gnat's sneeze and that's not what was observed.

Chombo said:
This may be a weird question, but oh well. Way back during the Scientific Revolution it would have been possible to define mass as acceleration divided by force right? Then you'd have F = a/m, and the units for force would be different than they are now.

Define your mass m' like this:

m'=1/m

And your Newton's law will be: m'=a/F

Chombo, I think your problem is, you didn't reflect what F = m * a actually means. Mass is define as the resistance of a body to change his velocity as a responce to force
With your definition, the bigger the mass of a body, the easier it would change its velocity.
Maybe this would be something just to get used to.
But furthermore you would lose the very nice property, that the mass of a composed body is the sum of the masses of its components.

The "standard" way of formulating known theory, including the definitions and unit systems are by no means unique. In most instances the "standard" way has come about because it is the easiest and most intuitive way of doing things.

The "standard" for unit systems we have adopted is the SI system, but people still frequently work in other unit systems. The imperial system for example is wholly consistent with known science, however the SI system is more widespread because unit conversions are so much easier (i.e. convenience). The SI system is not the most convenient in every case, CGS units are frequently used in electromagnetism because they streamline formulas by removing most of the recurring constants that pop up using SI units.

Claude.

Claude, what you write is true. But I think it is not quite hitting the point.

Chombo's proposal means a different definition of the physical quantity mass. This is a deeper change to physics than just the change from kilogramms to pounds.
Different units usually mean just a constant linear conversion factor.
The only exception I can think of is temperature where you have an additive constant involved when going from degrees Celsius to absolute temparature.
And even here you use different symbols for the temparature in degrees Celsius versus degrees Kelvin and probably talk about different physical quantities.
Chombo's definition clearly leads to a different physical quantity (maybe best called lightness) and not just to different units.

## 1. What were the units of mass used during the Scientific Revolution?

During the Scientific Revolution, the most commonly used units of mass were the pound and the ounce, which were derived from the Roman system of measurements. The pound was divided into 16 ounces, and each ounce was further divided into 16 drams.

## 2. How did the units of mass change during the Scientific Revolution?

The units of mass changed during the Scientific Revolution due to the development of new measurement systems. Scientists began using the metric system, which was based on the decimal system and used units such as the gram and the kilogram. This system was more precise and allowed for easier conversions between units.

## 3. Were there any other units of mass used during the Scientific Revolution?

Yes, there were other units of mass used during the Scientific Revolution. For example, the apothecary system, which was commonly used in medicine, used units such as the scruple, the dram, and the grain. However, these units were not widely accepted outside of the medical field.

## 4. Why did scientists switch to the metric system during the Scientific Revolution?

Scientists switched to the metric system during the Scientific Revolution because it was more accurate and precise compared to the older systems of measurement. It also allowed for easier conversions between units and was based on a logical, decimal system that was easier to understand.

## 5. Did all countries adopt the metric system during the Scientific Revolution?

No, not all countries adopted the metric system during the Scientific Revolution. While it gained widespread acceptance in Europe, countries such as the United Kingdom and the United States continued to use their own systems of measurement. It wasn't until much later that the metric system became the standard for scientific measurements worldwide.

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