[Contents]

The Feynman Lectures on Physics
John Denker

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