Classify the following measure as a scalar or a vector: $20 \, m/s^{2}$.

The position vectors of two points $A$ and $B$ are $\hat{i} + \hat{j} - \hat{k}$ and $2\hat{i} - \hat{j} + \hat{k}$ respectively. Then $|\overrightarrow{AB}| = $

Find the direction cosines of the vector $\hat{i}+2 \hat{j}+3 \hat{k}$.

If $\vec{a} + 5\vec{b} = \vec{c}$ and $\vec{a} - 7\vec{b} = 2\vec{c}$,then which of the following is true?

The vectors $b$ and $c$ are in the direction of north-east and north-west respectively and $|b| = |c| = 4$. The magnitude and direction of the vector $d = c - b$ are:

If $a$ is collinear with $b = 3 \hat{i} + 6 \hat{j} + 6 \hat{k}$ and $a \cdot b = 27$,then $|a| =$