When $n$ vectors of different magnitudes are added, we get a null vector. Then the value of $n$ cannot be
$11$
$4$
$3$
$2$
The vector sum of two forces is perpendicular to their vector differences. In that case, the forces
Two vectors $P = 2\hat i + b\hat j + 2\hat k$ and $Q = \hat i + \hat j + \hat k$ will be parallel if $b=$ ........
Explain commutative law for vector addition.