Talk:Physics with Calculus/Mechanics/Newton's Laws

Too Wordy?
This is my first edit here, so I'm unsure how well this fits in. I wrote a lot of description (probably of mediocre quality) due to my experiences at teaching undergraduates, where I noticed that a lot of them needed a lot of work in conceptual foundations in the early part of the course in order to be able to apply the math in later segments. Usually a lot of students seem to understand the math, but their lack of conceptual understanding means that they don't know how to apply the equations that they learned in class. I also could not find any guidelines on how heavy this work should be on conceptual explanations.

Feel free to cut out huge chunks. Alwyn 02:36, 4 October 2005 (UTC)

N3L Incorrectly Explained?
The present explnation of N3L uses Fg and normal force (Fn - from the chair)... which is part of the concept of balanced forces in N1&2L...

... but the correct corresponding N3L force for Fg from the earth downwards on the person would be the Fg of the person upwards on the earth.

This is a very common mistake I see time and time again and leads to continuing confusion by 1st year students on this topic. A believe a better (albit unconventional) explanation is to restate N3L as "All forces exist between two objects". There is only one force Fg that acts on both the person and the earth, pulling them together.

The example given in the present article then places a chair between the person and the earth and complicates the situation by adding two new sets of normal forces - between the top of the chair and the person, and between the bottom of the chair and the earth.

I would suggest a change to reflect what I believe is a clearer explanation.

Hope this helps! 72.141.79.59 02:04, 8 March 2006 (UTC)jonB