Errata for G. Loy, Musimathics,
Volume 1 (2007)
First see Gareth Loy's own
Errata.
This book is great for our course,
except in its faulty coverage of basic kinematics and
physics, for which an introductory college physics book such
as Giancoli's should be consulted, or even Rossing, Moore and Wheeler.
The following errors are present:
- p.14 last line: should read, `Real numbers include all integers,
all possible fractional values, and all irrationals as well'.
(Note the reals must include the irrationals: sqrt(2) is not a rational)
- p.22 Fig 2.10: penultimate note in F major scale is E not E#
- p.29, Fig 2.19: The plus signs in the list `f + 2f + 3f + ...' are
mathematically meaningless. If multiples of a frequency f are superposed,
the frequencies do not get added. Fig. 2.27 better represents partials.
- p.43, Fig. 3.1: As above, plus signs are mathematically wrong.
- p.104, (4.13) and preceding 2 eqns:
The formula a_average = s/t^2 is wrong, and is missing a factor of
1/2 (although it is still misleading).
This stems from a confusion
between average v and Delta v (change in velocity).
The paragraph surrounding (4.13) should be
ignored, and (4.12) should read same as (4.14).
This causes a bunch of quite serious trickle-down errors:
- p.111: 2nd and 3rd line of equations, should be entirely
cut since it is wrong and a misleading derivation of kinetic energy.
This style of derivation specifically would apply only to uniform acceleration
which is not mentioned.
- p.111, (4.28) missing factor of 1/2
- p.143, 8th line down: E_k=mv^2 missing factor of 1/2
- p.144: (5.27) missing factor of 1/2
- p.132, (5.8): alpha should be defined as the limit of
Delta omega / Delta t as Delta t goes to zero. The rest given is wrong.
This is analogous to the discussion of linear acceleration.
- p.134, bottom, in bold: Should read, `Circular motion is
the result of a centripetal
force applied at right angles to the instantaneous velocity.'
- p.194: there is an error persisting throughout this
page down to the final equation. If a speaker has intensity I,
then at twice the distance the intensity is I/4, not sqrt(I).
This mistake affects each equation on this page: sqrt should be replaced
by a factor 1/4, and squaring by a factor of 4.
- p.231 3 lines from bottom:
Statement that only relative velocity matters for 2D Doppler is wrong.
Just as with 1D Doppler, both source and receiver absolute motion
(ie relative to the air) matter.
- p.232: this whole page is incorrect and should be ignored;
2D Doppler is covered in other books. In brief, at position 3 there
*is* relative velocity, just not along the line-of-sight. I believe
Loy is using the symbol z_bar to mean line-of-sight velocity,
in which case it is given by ux/z not the complicated expression given.
This makes the main result (7.26) wrong.
- p.246: V = 7.5 * 10^4 or 7.5E4, but not 7.4^{-4}.
- p.460 Ch. 5 Note 4: Circular motion certainly is not the *vector sum*
of centripetal force and linear velocity. These two quantities have different
units so cannot be added!
Please contact me, Alex Barnett, with additions or corrections.
