fisica1-youn-e-freedman-exercicios-resolvidos

1.53: Use of the right-hand rule to find cross products gives (a) out of the page and b)
into the page.
1.54: a) From Eq. (1.22), the magnitude of the cross product is
o o
2
( 12 .0m)( 18.0m) sin ( 180 − 37 ) = 130m
The right-hand rule gives the direction as being into the page, or the – z-direction. Using
Eq. (1.27), the only non-vanishing component of the cross product is
C
z
= A B
x
y
=
o
2
( sin37 ) = 130m
( − m) ( 18.0m)
12 −
b) The same method used in part (a) can be used, but the relation given in Eq.
(1.23) gives the result directly: same magnitude (130 m 2 ), but the opposite
direction (+z-direction).
1.55: In Eq. (1.27), the only non-vanishing component of the cross product is
( 4.00)( − 2.00) − ( 3.00)( 5.00) = −23.00,
C
z
= Ax
By
− AyBx
=
A
r × B
r
= − 23.00
kˆ
and the magnitude of the vector product is 23.00.
so ( ) ,