## In This post you will get answer of Q.

The unit mass having $r = 8hat{ i} – 4hat{ j}$ and $v = 8 hat{i} + 4hat{ j}$ in its angular momentum is

Solution:

## For a body of mass m rotating with velocity v in a circle of radius r, the angular momentum is given by

$L=m(r times v)$

For unit mass, m = 1

hence $|L|=(8 hat{i}-4hat{j})times (8hat{i}+4 hat{j})$

$ |L|=begin{vmatrix}

hat{i}& hat{j} & hat{k} \[0.3em]

8 & -4 & 0 \[0.3em]

8 & 4 & 0

end{vmatrix}$

$|L|=hat{i}(0-0)-hat{j}(0-0)+hat{k}(32+32)$

$Rightarrow |L|=64 hat{K}$ unit