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As I recall there was a pound mass, and a pound force defined at
one time.
Currently engineers still are taught the slug mass and pound force.
The "common" definitions are hopelessly at odds with each other,
and confused. Even the Natl Bureau of STD at least in one place
equates mass with weight.
As to confusion caused by authors, some should know better. An
astrophysicist and respected author wrote a hopelessly wrong
explanation of Newton's third law for the World Book Encyclopedia.
In it he uses motion to explain how action = reaction, and never
mentions force.
So of course when he mentions a ball bouncing off of a wall, the
action obviously does not equal the reaction. Now if he had used
momentum, he would have been correct. Also he repeats the idea
that negative acceleration is always slowing down. This is a
common interpretation which is a resistant misconception.
Do our own people have to try to be so popular that they have to
repeat these misconceptions, and imbed them deeper in student
psyches?
If anyone knows the man perhaps they could communicate with him
about the problem. I sent him an E-mail, but he does not know who
I am and assumes I am a kook, which may be true. Anyone who wishes
to write physics accounts should read a bit of the research about
misconceptions and how language should be used to promote clear
communication about science.
The world book is a major resource for students and families. The
Wikipedia is accurate, but hopelessly difficult for students who
are not engineers or physicists.
There is a website www.brainpop.com <http://www.brainpop.com> that is presenting lessons on
many topics including science. They should be ashamed of the
outrageous misconceptions that they are promoting in both the
movies and the quizzes they distribute. It is used by a number of
teachers and districts have bought access to it. Don't they have
physicists parsing their material?
The answer is rhetorical because they obviously don't
John M. Clement
Houston, TX