Problem 3-25b - Vector difference - Part 5 - (C)

Determine the vector that must be added to the sum of \(A\) and \(B\) in the figure to give a net displacement of \(4.0\; km\; \text{W}\).

diagram indicating directions north and east as well as vectors A and B


Accumulated Solution

diagram indicating C at the desired 4 km West

Solution \(A_x\) \(B_x\) \(C_x\) \(R_x\)
(A) 5.1 cos 71 6.8 sin 52 \(C_x\) -4

 

Solution \(A_y\) \(B_y\) \(C_y\) Ry
(B) \(-5.1 \sin 71\) \(6.8 \cos 52\) \(C_y\) \(0\)

\(5.1 \cos71 + 6.8 \sin52 + C_x = -4 \\ -5.1 \sin71 + 6.8 \cos52 + C_y = 0\)

\(C_x = -11 \;km \\ C_y = 0.63 \;km\)

\(|C| = 11 \;km\)


Correct

\(\theta = tan^{-1}C_y/C_x = tan^{-1} \;0.63/11 = 3.3^\circ\)

 

In which direction is this?

(A)    north of west

(B)    south of west