[Donaldson Tan]

Light years is an other example. Way more convenient for astronomers to talk in light years than 10^17meters

don't astronomers use parasec to measure inter-stellar distances? instead of using kg, it's more practical to express the mass of stars and planets in term of solar mass. even chemist/physicist use a.m.u to measure the mass of nuclei?

[Borek]

Ease of use, complete range coverage, universality (additional units based on existing ones, like volume measured in units based on meter).

[Borek]

don't astronomers use parasec to measure inter-stellar distances?

AFAIK both ly and pc are used.

instead of using kg, it's more practical to express the mass of stars and planets in term of solar mass. even chemist/physicist use a.m.u to measure the mass of nuclei?

In many situations it is much more convenient to use some specific scale, like mole. However, metric system is a common denominator that makes any conversion easier, faster, and less prone to errors. It doesn't make sense to measure anything in different units, it doesn't make sense to measure everything using the same units. Some balance is needed.

[Mitch]

Its also easier to measure pressure at sea level as 1 atmosphere rather than the "proper" SI equivalent of 1013250dynes/cm².

[lemonoman]

Is the dyne a metric unit?  I thought is was Pascals...but maybe I'm cofusing SI with metric...?

[xiankai]

for your qn no.3 ... list all the examples in real life which show the efficiency of the metric system, easiest way to fill up an essay with pointless information  

as for dynes... i though pressure was measured in pascals/newton squared metres?

dyne seems to me like the centimeter version of newtons.

[AngelShare]

for your qn no.3 ... list all the examples in real life which show the efficiency of the metric system, easiest way to fill up an essay with pointless information  

as for dynes... i though pressure was measured in pascals/newton squared metres?

dyne seems to me like the centimeter version of newtons.

That's what I was going to do but my mind is blank...what could a scientist be doing? How on Earth am I to guess what a scientist may be doing with the metric system?

Stupid question...

[xiankai]

everyday applications like figuring out much is needed for a cooking recipe, calculating your daily calorie intake, etc.

it doesnt have to be lab-based; heck, most people visualise scientists in white coats working with test-tubes in a lab. check out our member gallery photos and u'll know there's more to meets the eye than it is.  

if u really want to be specific, u can try what Borek said

Ease of use, complete range coverage, universality (additional units based on existing ones, like volume measured in units based on meter).