y/Discussion question E.
The easiest method is the one demonstrated in example 62 on
p. 203. Casting vectorFN 1 ’s shadow on the ground, we can tell
that it would point to the left, so itsxcomponent is negative. The
only two possibilities for itsxcomponent are therefore−FN 1 cosθ
or−FN 1 sinθ. We expect this force to have a largexcomponent
and a much smallery. Sinceθis small, cosθ≈1, while sinθis
small. Therefore thexcomponent must be−FN 1 cosθ.x/Example 71 and problem 81 on p. 239.Discussion Questions
A An object goes from one point in space to another. After it arrives at
its destination, how does the magnitude of its∆rvector compare with the
distance it traveled?
B In several examples, I’ve dealt with vectors having negative com-
ponents. Does it make sense as well to talk about negative and positive
vectors?
C If you’re doinggraphicaladdition of vectors, does it matter which
vector you start with and which vector you start from the other vector’s
tip?
D If you add a vector with magnitude 1 to a vector of magnitude 2,
what magnitudes are possible for the vector sum?
E Which of these examples of vector addition are correct, and which
are incorrect?
F Is it possible for an airplane to maintain a constant velocity vector
but not a constant|v|? How about the opposite – a constant|v|but not a
constant velocity vector? Explain.210 Chapter 3 Conservation of Momentum