Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

[Phys-L] Re: Interesting quotation about percentages



Yes, yes, yes, but pls, not a stopwatch. I use a marble falling along a
meter stick. The student, pick a Jock who claims a fast reaction time,
places its hand at the mottom of the vertical meter stick. The marble is
dropped from various heights, the student moves its hand out of the way at
the instant of release. The minimum height for evasion of the marble then
gives the reaction time (ordinarily about 1/4 -1/2 second, as I recall).
Then use this reaction time in a problem where two cars are following each
othe with a separation of {say) 1 meter at a speed of 30 mph. The lead
car hits the brakes, the second car hits the brakes 1 reaction interval
later. The two cars decelerate with the same deceleration, say 1/2 g, but
the delay guarantees a constant closing rate during deceleration, contrary
to most person's intuitions.

I usually did this on the second day of an intro physics course.

Motion of the hand to evade the falling marble simulates the act of moving
foot from accelerator to brake pedal.
Regards,
Jack



On Sat, 30 Apr 2005, Bernard Cleyet wrote:

I don't quite agree. The original statement is always correct. To see
what I mean, I rewrite: 3% exceeds 2% by 50% AND by one percentage
point. Carl also suggested another method less commonly used, i.e.
percents, note the "s". However, it is cacophonous when the amount is one.

For sometime I've been frustrated by the two conflicting uses of
percentage. One as a concept or algorithm and the other as a unit.
Recently I've noticed in the popular media (news papers, TV, etc.) the
use of point(s) w/ the latter meaning.

bc, no longer frustrated.

Carl Gaither wrote:

Hello to the List--

I believe that this quotation and Brian's response show's a source of human
error.

Firstly, let's rephrase the quotation slightly to "Three apples exceeds 2
apples by 50 percent not 1 apple".

Here it doesn't take much to agree that this statement is true if we are
looking for the solution in percentages and not in excess apples. I
perceive Denison's statement the same as the statement with the apples.
Denison was indicating a solution based on percentages and not excess
percents. Hence, human error enters into the solution of the problem at the
moment an individual interprets the problem.

-----Original Message-----
From: Forum for Physics Educators [mailto:PHYS-L@list1.ucc.nau.edu]On
Behalf Of Brian Whatcott
Sent: Friday, April 29, 2005 8:11 PM
To: PHYS-L@LISTS.NAU.EDU
Subject: Re: Interesting quotation about percentages


At 07:00 PM 4/29/2005, you wrote:

Hello to the list--

I came across this very interesting quotation by Edward Denison--

"Three percent exceeds 2 percent by 50 percent, not by 1 percent".

I hope that you enjoy it.

Carl Gaither


Rendered literally, this becomes..

0.03 in 1.0 exceeds 0.02 in 1.0 by 0.5 in 1.0 not by 0.01 in 1.0

...and is much less convincing.



Brian Whatcott Altus OK Eureka!




--
"Trust me. I have a lot of experience at this."
General Custer's unremembered message to his men,
just before leading them into the Little Big Horn Valley
_______________________________________________
Phys-L mailing list
Phys-L@electron.physics.buffalo.edu
https://www.physics.buffalo.edu/mailman/listinfo/phys-l