**Errors in Aug 2010
version of Ruina/Pratap
**Help us improve the book: send email to ruina@cornell.edu

Please suggest improvements. For example, if you have trouble finding something, even if you did eventually find it, we'd like to know. Or, do you think any explanations are weak? Give us some clues about your difficulties learning with this book.

**Make money** if you are the first to find an error: $1.00 for
math errors, $5 for real errors or things that need deep fixing (with
suggestion about how to fix). How?: Subject
line in email: TEXT ERRORS. Then list like the Known Errors below,
(XX are your initials), e.g.,

Sect 13.2, pg 642, paragraph above "More about pendula". -XX 2/5/09

In the argument of the exponentials change gt/l to +- sqrt(g/l)t.

**Known Errors**

We keep track of typos, case and tense mismatches, mising closing parentheses,
spelling and grammatical errors, etc, but don't list them all here. The errors
below are more serious.

* = an appropriate
repair has already been made in the source file

! = non-trivial error, readers should note.

**! Section 2.1, page 45, 1st equation:** -IV 8/25/10

rB/A = -rB/A should be
rB/A = -rA/B

**! Section 2.3, page 68, item 7:** -BE 8/26/10

As written there is a vector minus a scalar. *Bad.* The second term inside the
absolute value sign needs to be multiplied by rB/A
/ |rB/A|. That is, as written the second term is the length of the projection
along the line. That needs to be multiplied by a unit vector along the line
to make a vector to subtract from rC/A.

**! Section 2.3, page 69, paragraph over the first "Example"** -
CO 8/29/10

Change
AxB = (A1B2 - B2A1)e3 (As incorrectly printed, the cross product is zero.)

to AxB
= (A1B2 - A2B1)e3.

**! Section 2.3, Sample 2.19, page 77: **-SC 9/13/10

Change A(-1,4) to A(-1,1)

**! Section 2.4, pg 88, Moment about an axis example**, - SC 9/18/10

Change -17/sqrt(2)
mN to -41/sqrt(2)
mN

**! Problem 2.7.11b, page 146.** - EE 9/06/10

The cutout circle is not drawn to scale, it actually encompasses the center
of the big circular plate.

**! Problem 4.5.10, page 252 **-KS 9/8/10

change IE to
CE

change I,C and B to C
and B

**! Pages 285-6, truss matrices setup.** -Dan Levine
10/31/10

There are a few errors in the matrix setup which are corrected here.

**! Problem 5.2.7, page 314**, -JZ 9/17/10

On the figure change the base lengthAF from 2L
to 3L.

(as printed, points C and D coincide)

**! Problem 5.3.6, page 315**, -AR 9/20/10

On the figure there should be rollers at E (and the figure should be bigger).

**Sect. 6.3, pg. 357,** "Pulley and Chain Drives" bottom
of par. 1. -KL10/08/10

Change "Fig 6.53B" to "Fig
6.55B"

**! Problem 6.2.8, page 368 **-AR 9/17/10

Delete the problem. The problem is not well enough defined. No simple fix.

**Problem 6.3.2, page 371** -SP 10/13/10

dimension of bottom length is \ell (script letter L)

***Problem 6.3.14, page 373** -AR 10/13/10

Figure needs various clarifications.

**! Problem 8.1.3, pg 409** (& 1007), Answer -NAS 10/17/10

Change 5.85 x 10^5N to 5.85x10^4N.

**! Sample 14.32, page 826.** -MC 2007

Here is an extensive correction to this sample by Mike Coleman.

Also v_D should be v_0.

and
v_P should be v_G.

First and second figures need A' (not A) on disk.

**Section 16.1, Sample 16.8.** Some ideas from Les
Schaffer.

Do the frictionless case of Sample 16.8 in the
text.

Point out that the increase in kinetic energy is the work of the contact
force.

In the sample, use a dot product with e_r + mu e_theta to get the equation of
motion in one less step. In the sample point out that the work of the constraint
force is the change of kinetic energy.

Send comments to ruina@cornell.edu.