See reference 1.

1  Some Observations

1.

[bug] Starting on page 4-4: Weight is a force, and the book measures weight in pounds. There is an ill-founded rumor that the pound is a measure of force, but according to US regulations the pound is defined as a measure of mass, and always has been, as far as I can tell. For details, see reference 2.

2.

On page 4-4, equation 4.3 leaves no doubt that “weight” is synonymous with the “force of gravity”. Similarly, on page 4-6, g evidently denotes the local acceleration of gravity. Furthermore, equation 4.6 implies that the weight W is equal to mg. This is OK. I mention it only by way of contrast with item 4.

3.

On page 4-5: Epitaph of Stevinus

4.

On page 7-1 and again on page 7-9, we find Newton’s law of universal gravitation, «F = G m m′ / r²». Also, on page 12-9, combining equation 12.8 and 12.9, we find another statement of this law, applicable to extended bodies (not just point particles). This is a problem, because this “force of gravity” is numerically and conceptually different from the “force of gravity” in item 2.

5.

[bug] On page 8-8, the acceleration is given as «a = dv/dt = 32». According to modern practice, this fails the basic dimensional-analysis check. It should be 32 ft/s².

6.

On page 9-2, we find the second law of motion: «F = m dv/dt = m a».

7.

On page 12-5, the notion of pseudo-force is introduced.

8.

[bug] On page 12-9, in equation 12.9, there should be a summation sign on the RHS.

2  References

1.

Feynman, Leighton and Sands,
The Feynman Lectures on Physics
(three volumes; Addison-Wesley, Reading, MA, 1963–1965).

2.

John Denker,
“Definition of Weight, Gravitational Force, Gravity, g, Latitude, et cetera”
www.av8n.com/physics/weight.htm