If $\vec{P}+\vec{Q}=\vec{P}-\vec{Q}$,then

$A$ football player is moving southward and suddenly turns eastward with the same speed to avoid an opponent. The force that acts on the player while turning is:

Two vectors having equal magnitudes $A$ make an angle $\theta$ with each other. The magnitude and direction of the resultant are respectively

Explain the subtraction of vectors.

The resultant of two vectors $\vec{A}$ and $\vec{B}$ is perpendicular to $\vec{A}$ and its magnitude is half that of $\vec{B}$. The angle between vectors $\vec{A}$ and $\vec{B}$ is . . . . . . (in $^{\circ}$)

Two forces $P + Q$ and $P - Q$ make an angle $2 \alpha$ with each other,and their resultant makes an angle $\theta$ with the bisector of the angle between them. Then: