Why is a system of units important in physics?

Answer 1

For the same reason adjectives are important to language: they allow precision and a common frame of reference.

If you tell me that something is 10 miles away, then we're both clear on what that means. If you tell me something is 10 away, I have no idea what you're talking about.

Not only is a system of units important, but to be useful, the units must have a rigid definition. The "hand" as a unit of measurement literally meant someone's hand, and everyone's hand is sized differently. Same issue with paces: if I tell you that something is 100 paces away, you'd have to know exactly how much 1 of my paces is.

Answer 2

The conventional, old system of units did prevail for quite some time before the need for a new system of units arised. The new system had to be universally the same, without being peculiar to an area. So, the new system that was introduced is called the S.I System (System International). In 1960, a conference of the world famous scientists took place in Paris, where they introduced the above mentioned system. It includes of 7 basic units, i.e.

S. No QUANTITY S.I UNIT
1) Length, Meter (m)
2) Mass, Kilogram (kg)
3) Time, Second (s)
4) Temperature, Kelvin (k)
5) Quantity of
substance, Mole (n)
6) Light Intensity, Candela (cd)
7) Electric Current, Ampere (A)

Hope this would help you.

Answer 3

A system of units is particularly important in physics as the different units can combine (in multiplying forces) or cancel out (in dividing forces) to form a new unit that is quicker to write out and more easily recognisable.

For example:
Force = mass x acceleration

The unit of mass is kilograms (kg) , and the unit of acceleration is metres per second (ms^-2)

So the unit for Force could be written as kg m s^-2. But these 3 separate systems of units can combine into one simple unit called a Newton (N).

It just makes the answers look neater and can lead to complex equations being more easy to deal with.

Answer 4

You need to use measurements that have a specific relationship to each other or your measurements will be meaningless. You will be adding an extra variable and make any calculation impossible. If I say that there is one calorie in one Cheerio(just a guess, don't quote me on that) and 29 grams in a serving, you will need more information to know how many Cheerios to the gram or how many calories to a serving. You can use both metric and U.S. measures but it is much easier to use one system of measurement. Otherwise you will spend too much time and get too many headaches converting from metric to US measures and trying to keep it straight which units are for weight vs. mass vs. force, etc.

Answer 5

Standard systems of unit are important in anything - how would you measure apples and plates, for example? A plate could be 5 apples wide, or 3 - depending on how large the apples were!

Answer 6

I come from the time when metrication was just coming in.
One guy was measuring things in Drams (1/16th ounce) the other in Grams (25.4 to the ounce.) for flavour dosages.
That caused some interesting effects!
An American pint is 16 ounces, an English one 20 ounces. Now work out the size of their gallons at 8 pints to the gallon in both cases!
Standardisation is needed.
RoyS

Answer 7

it is a communication mechanism. if there were no standardisation then no-one would know what anyone else meant, just like language. It also interelates quanities e.g.
It takes 1 joule of energy to raise 1kilogram of water through 1 degree centigrade (i think :)