Antonio Lao said:
Thanks. In other words, removing coordinate system changed the 'direction' of the system?
I'm not so sure it "changed" the direction of the system, since the expressed vector was held in potential all along. It simply became expressed as the system translated from one state to another.
Also, I would caution against manipulating dependent mathematical terms to the effort of "cancellation" Many mathematical equations are written to describe a valued dependency, such as f=ma.
This dependency often(though not always) requires that a value be ascribed to each term. If one cancels mass, then f=a, which makes the equation non-sensical. Rather than cancelling mass, the value should be set as zero. As such, f=0xA, which makes more sense.
In other words, one cannot "exclude" the mass term from a mathematical expression that is dependent on it. It must be given a value, even if that value is zero.
In other words, algebraic manipulation in some equations may well reflect the abilities of that manipulation, but may yet have no true basis in reality.
Perhaps put another way, let's say that a=bc. With respect to using numbers, this equation is correct, and with certain extensions "b" can be cancelled. However, f=ma is NOT strictly a numerical equation. It is a "concept-dependent" equation, and follows different rules.
Let's consider another example.
Take the standard simple formula used in electronics, p=ie, which means power equals current times voltage. This is a dependency relationship.
You can have voltage without current, but you cannot have current without voltage. Agreed?
If you "cancel" voltage from the equation through extension the entire equation collapses, because it invalidates the other term, current. So, since current cannot exist without voltage, voltage is never "cancelled" It's value might be zero, but the term itself is not canceled from equation CONSIDERATION. Get it?
Similarly, mass can exist without acceleration, but acceleration cannot exist without mass. Therefore, any equation which uses acceleration in it's term CANNOT have mass "cancelled", only it's value set to zero.