Question

I have a question about 'base quantity'.
Actually, velocity, power, work, etc are derived from 'meter, second, kilogram'. but, is there any absolute evidence that 'meter, second, kilogram' are base quantity? Help me please! I'm just curious about these. It's good for me to see simple answer. except 'yes. no.' ^_^

Answer 1

My take on it is that there is nothing special about base quantities.... except that they can be accurately measured. For example, you might think Charge (coulombs) should be a base quantity, but instead Current (amperes) is - but current is the amount of charge per unit time (in coulombs/second), so shouldn't charge be the base quantity? Instead, it turns out that current can be more accurately measured than charge, so it is the base quantity.

Answer 2

There is more info on this matter at the NIST website... http://www.nist.gov/index.html

Answer 3

ho! It is helpful that 'there is nothing special about base quantities except that they can be accurately measured'. ! thank you!

Answer 4

In mechanics, yes. One can define all mechanical quantities in terms of mass, length, and time. However, some physicists like using a completely different unit system in which the base system is plank's constant-the speed of light-and the gravitational constant. Both systems are equivalent.