A force of $5 N$ acts on a particle along a direction making an angle of $60^{\circ}$ with vertical. Its vertical component will be $………\,N$

The angle between the two vectors $\vec A = 3\hat i + 4\hat j + 5\hat k$ and $\vec B = 3\hat i + 4\hat j + 5\hat k$ is ……. $^o$

Four persons $P, Q, R$ and $S$ are initially at the four corners of a square of side $d$. Each person now moves with a constant speed $v$ in such a way that $P$ always moves directly towards $Q, Q$ towards $R$. $R$ towards $S$, and $S$ towards $P$. The four persons will meet after time ……..

If $\vec{A}+\vec{B}+\vec{C}=0$ then $\vec{A} \times \vec{B}$ is …………

The vector sum of two forces is perpendicular to their vector differences. In that case, the force