Kinematics Question 294
Two vectors A and B have equal magnitudes. Then the vector A + B is perpendicular to
Options:
A) x-axis
B) y-axis
C) z-axis
D) Line at equal angles to all the three axes
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Answer:
Correct Answer: A
Solution:
$ \vec{L}=\vec{r}\times \vec{p}= \begin{vmatrix} {\hat{i}} & {\hat{j}} & {\hat{k}} \\ 1 & 2 & -1 \\ 3 & 4 & -2 \\ \end{vmatrix} $
$ =-\hat{j}-2\hat{k} $
i.e. the angular momentum is perpendicular to the x-axis.
BETA
