1. The problem statement, all variables and given/known data
(Problem about a collision) (…). What then is their velocity in (a) unit-vector notation and as (b) magnitude and (c) angle.

I will not post the problem due to copyright issues and that it is absolutely pointless now.

3. The attempt at a solution
I was able to solve (a) and (b).
However, my answer for (c) differs from that of the textbook.
$$\text{a)} \;(2.67 \;\text{m/s})\hat{i}+(-3.00 \;\text{m/s})\hat{j}$$
$$\text{b)} \;4.01 \;\text{m/s}$$
$$\text{c)} \;\theta{} = \tan^{-1}\left(-\frac{3.00}{2.67}\right)=-0.845397=-48.4^{\circ{}}$$

While the book provides +48.4° as the angle.

Am I correct? You can solve (c) from (a) and (b) [my answers are identical to those of the book].

It is from Fundamentals of Physics (Extended) – 9th ed.

http://ift.tt/1iIQjNA