Happy Christmas all!
I am convinced that we are trying to grapple with complex "end state" examples whilst we have not sorted the basics out. If we agree on the basic rules, then we can agree on explanations for the following examples that we have thus far discussed without solution:
1. David with his rock in a sling Vs Goliath.
2. A girl holding a chain on a merry go round.
3. A marble on a rotating disc.
4. An Alcohol pump.
5. Droop stops on a rotor disc.
6. A car going around a round about.
7. A steel ball on a chain.
8. A tractor on a chain around a stump.
9. Liquid dye on a rotating disc.
10. Sattelites and orbits.
Thats a lot considering we have not progressed at all.
Here is my suggestion:
A. we stop introducing yet another example, they are all the same (gravity excluded). Let us just use the last one: a steel ball on a chain.
B. We start with basics first.
I think there are some critical steps in the basics that, if we sort out, will lead us to explanations of the more complex issues. I am in agreement with heedm and FS that the first sticking point is acceleration. The first question is then:
1. Is velocity directional?
If so, then any change in direction is a change in velocity. And an acceleration IS a change in velocity. Thus a change in direction requires an acceleration.
Any disagreements with this so far?
<img src="smile.gif" border="0">