The acceleration of an object on the surface of the earth is 9.8 m/s^2

How Do I Think?

How do I form thoughts? Process Them? And make sure I understand a concept?

Do i just gloss over them? How do i really really understand?

When I have committed them to memory, do i really understand a concept?

When I could link them to previous knowledge that I have, do I understand something?

Say.

A concept:

The acceleration of an object on the surface of the earth is 9.8 m/s^2 .

Do i understand such a concept?

Or have i just memorized that concept.

If that object is at the surface of the earth. Does it have an acceleration? What is the concept of acceleration in the first place?

Acceleration , by definition is the rate of change of velocity over time.  So if an object’s velocity is not changing, that means there is no acceleration as well.  Ergo, the statement the ‘acceleration of an object on the surface of the earth is 9.8m/s^2 is wrong. No, not wrong. Rather it is imprecise.  A more precise statement would be, an object in free fall on the surface of the earth has an acceleration of 9.8 m/s^2.  But in making our statement more precise, we introduced another concept : free fall. Do i understand what free fall means? Free fall, means no outside forces besides the force of gravity is acting on our object.  By stating such, that would imply that nothing is acting on it besides the force of gravity.  As in NADA - no air resistance, no normal forces, no impulsive forces, no string tied to it, no rubber band.

So finally, have we understood the concept:

an object in free fall on the surface of the earth has an acceleration of 9.8 m/s^2

?

I think we do:

First we note that an object with no other forces acting on it besides the force of gravity, will change its velocity by the rate of 9.8 m/s per second.  So whatever initial velocity it has, then the next second it would have changed by an amount of 9.8 m/s .  So if an object intially, has zero velocity, then the next second its velocity should be 9.8 m/s.


So we come back to our initial thesis.

When do we say we understand a concept?

- when we can restate the concepts involved in another fashion? When we can demonstrate what are the consequences of such a concept? When we can demonstrate how it will affect a certain situation?


- let’s go with that for now. :D