Explain subtraction of vectors.
Subtraction of vectors can be defined in terms of addition of vectors.
We define the difference of two vectors $\overrightarrow{\mathrm{A}}$ and $\overrightarrow{\mathrm{B}}$ as the sum of two vectors $\overrightarrow{\mathrm{A}}$ and $-\overrightarrow{\mathrm{B}}$.
$\overrightarrow{\mathrm{A}}-\overrightarrow{\mathrm{B}}=\overrightarrow{\mathrm{A}}+(-\overrightarrow{\mathrm{B}})$
Thus, substraction of vectors means adding opposite of a vector in another vector.
In figure (a), $\vec{A}, \vec{B}$ and $-\vec{B}$ is represented.
In figure (b), $-\vec{B}$ is added to $\vec{A}$.
By triangle method for vector addition,
$\overrightarrow{\mathrm{R}_{2}}=\overrightarrow{\mathrm{A}}+(-\overrightarrow{\mathrm{B}})$
$\therefore\overrightarrow{\mathrm{R}_{2}}=\overrightarrow{\mathrm{A}}-\overrightarrow{\mathrm{B}}$
(For comparison, $\overrightarrow{\mathrm{R}_{1}}=\overrightarrow{\mathrm{A}}+\overrightarrow{\mathrm{B}}$ is shown).
The coordinates of a moving particle at any time $t$ are given by $x = a\, t^2$ and $y = b\, t^2$. The speed of the particle is
Assertion $A$ : If $A, B, C, D$ are four points on a semi-circular arc with centre at $'O'$ such that $|\overrightarrow{{AB}}|=|\overrightarrow{{BC}}|=|\overrightarrow{{CD}}|$, then $\overrightarrow{{AB}}+\overrightarrow{{AC}}+\overrightarrow{{AD}}=4 \overrightarrow{{AO}}+\overrightarrow{{OB}}+\overrightarrow{{OC}}$
Reason $R$ : Polygon law of vector addition yields $\overrightarrow{A B}+\overrightarrow{B C}+\overrightarrow{C D}+\overrightarrow{A D}=2 \overrightarrow{A O}$
In the light of the above statements, choose the most appropriate answer from the options given below
Following sets of three forces act on a body. Whose resultant cannot be zero
When $n$ vectors of different magnitudes are added, we get a null vector. Then the value of $n$ cannot be