The vector
Has components +5 and +7 along the x and y axes respectively.If the vector is now rotated 90 degrees counterclockwise relative to the original axes,the vector's components are now
A)−7;−5.
B)7;−5.
C)−7;5.
D)7;5.
E)7;0.

Question

The vector 
Has components +5 and +7 along the x and y axes respectively.If the vector is now rotated 90 degrees counterclockwise relative to the original axes,the vector's components are now
A)−7;−5. 
B)7;−5. 
C)−7;5. 
D)7;5. 
E)7;0.

Quizplus · Accepted Answer

When the vector is rotated counterclockwise by 90 degrees, its x and y components will switch positions and one of the components will be negated. Negating the +5 x-component gives -5. Therefore, the new components are -5 and +7, which corresponds to choice C, (-7, 5).

The Vector Has Components +5 and +7 Along the X and Y