Question

The vector product of vectors A⃗  and B⃗  has magnitude 12.0 m2 and is in the +z-direction.Vector A⃗  has magnitude 4.0 m and is in the −x-direction. Vector B⃗  has no x-component.

Part A: What is the magnitude of vector B⃗ ? (I solved this question the answer is 3 and it's correct)

Part B: What is the direction angle θ of vector B⃗  measured from the +y-direction to the +z-direction? (This is the part that I didn't get it correct)

Answer 1

PART 3:

Given that the vector product of A and B is along positive z-axis.

Hence, the vectors A and B are lying on the x-y plane.

Also, we have, vector A is directed along -x direction and vector B has no x-component, means that vector B is perpendicular to x-axis also.

Hence, We can say that B is directed along positive +y-axis (using right hand thumb rule).

Hence the angle θ is given by:

(Note : If this answer shows wrong, another option is θ = 270^o. This is also possible)