# A particle of mass 2 kg is moving with velocity $2 \hat i + 3\hat j$. Its angular momentum about the origin when the particle is at $(1,1,0)$

$\begin {array} {1 1} (a)\;\hat k & \quad (b)\; 2 \hat i \\ (c)\; 3 \hat j & \quad (d)\;5 \hat k \end {array}$

$\overrightarrow {r}= 1 \hat i + 1 \hat j$
$\overrightarrow {p}= 2 \hat i + 3 \hat j$
$\bar {r} \times \bar {p}=3 \hat k -2 \hat k$
$\qquad= \hat k$
hence a is the correct answer
edited Jun 21, 2014