PHYSICS XI Ch#2 Quiz 1

Only change happen when multiply by a negetive number otherwise only magnitude change

When two equal vectors are anti parallel to each other then their resultant will be zero

Rectangular components are components making angle of 90 degree with each other 

As the vector A is directed only along the y axis therefore no horizontal component and whole magnitute is along vertical direction.

As the anti parallel vectors are opposite in direction so they can cancel the effect of each other and minimize the resultant

In 3rd quadrant the both components of vectors are negative so its direction will be in between 180 degree and 270 degree

As 3 N and 4 N are rectangular components so by using formula of magnitude answer will be equal to "5"

The unit vectors are mutually perpendicular (angle between them is 90 degree) to each other so the angle between them is 90 degree and for dot product  cos90=0 so i.j=j.k=k.i=0

As the dot product of given vector gives zero resultant so the angle between the given vectors is equal to 90 degree 

Reason#1:(cos90=0)

Reason#2: ( i ̂+ 3 j ̂-2k ̂ ).(i ̂-j ̂-k ̂ )=1-3+2=0