In: Physics
1) Two vectors, r and s lie in the x y plane. Their magnitudes are 4.84 and 6.09 units respectively, and their directions are 341o and 65.0o respectively, as measured counterclockwise from the positive x axis. What are the values of vectors (a) r . s and (b) | r × s |?
2) For the following three vectors A B C, what is 3⋅C . (3A × B)
?
A =3.00î + 2.00ĵ - 3.00k̂
B =-4.00î + 3.00ĵ + 3.00k̂
C =6.00î - 7.00ĵ
given
|r| = 4.84
|s| = 6.09
r =
341o
s =
65o
rs = (
341 - 65 )
= 276o
a )
r.s = |r| |s| cos
rs
= 4.84 x 6.09 x cos276
r.s = 3.081 units
b )
r x s = |r| |s| sin
rs
= 4.84 x 6.09 x sin276
r x s = - 29.314 units
2 )
given
A = 3.00 î + 2.00 ĵ - 3.00 k̂
B = - 4.00 î + 3.00 ĵ + 3.00 k̂
C = 6.00 î - 7.00 ĵ
3C . ( 3A x B )
3C = 3 x ( 6.00 î - 7.00 ĵ )
= 18 i - 21 j
3 A = 3 x ( 3.00 î + 2.00 ĵ - 3.00 k̂ )
= 9 i + 6 j - 9 k
| i j k |
( 3A x B ) = | 9 6 -9 |
| - 4 3 3 |
= i ( 18 + 27 ) - j ( 27 - 36 ) + k ( 27 + 24 )
( 3A x B ) = 45 i + 9 j + 51 k
3C . ( 3A x B ) = ( 18 i - 21 j ).(45 i + 9 j + 51 k)
= ( 18 x 45 ) + ( -21 x 9 ) + 0
3C . ( 3A x B ) = 621 units