Walter's comments re Velocity and Speed, etc.

Walter & Group :

 

 

Walter....

 

I'm learning a great deal from you engineers !

 

For one thing, I always thought in terms of velocity being a synonym for speed.

 

Thanks,

 

Gordy

 

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Gordy - on your point 3 - Force = load = mass x acceleration. Since the mass of the system remains

constant the acceleration is greates when the load is greatest; however, the velocity is still increasing

as long as there is acceleration (velocity = acceleration x time). Acceleration is positive up to the point

where there is no load on the road (i.e. RSP). The velocity is therefore greatest at RSP. This is confirmed

by the fact that the loop forms when the line speed exceeds the speed of the rod tip which is also at

RSP.

 

Now for the caveats. It took me quite a while to understand Noel Perkins paper because he uses

the terms velocity and speed in their correct physical terms, i.e. velocity is a vector quantity and

speed is not. At first reading I thought he was confusing the two but he was extremely accurate

in their use and everything made great sense to me once I realized that.

 

So why do I bring up the caveats? Because my first paragraph is only true if the force is applied in a

translational fashion only. It isn't. We go to great pains to maintain RSP of the rod tip which would

mean the force applied to the line is translational in nature so that the system defined in paragraph

1 is maintained; however, at the point of loop formation we want the rod tip to get out of the way

of the line (for reasons best described by Lefty). This means that there is a bit of acceleration

applied towards the ground to get the rod tip to move down. So the rod is not perfectly at RSP

at the instant the loop formation begins.

 

Cheers

 

Walter