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Motion In A Plane

Question
CBSEENPH11018238

What are rectangular components of a vector? How will you resolve the rectangular components of a vector in a plane?

Solution
When the resolved components of a vector are mutually perpendicular to each other, they are called as rectangular components. 
Let us resolve the rectangular components of a vector. 
The resultant of the vector is represented by OP with rightwards harpoon with barb upwards on top in XY plane. 
 
Now, from point P, draw a perpendicular PM on X-axis and PN on Y-axis. 
Now, using the triangle law of vectors to increment OMP comma spacewe have 
straight R with rightwards harpoon with barb upwards on top space equals space stack O P with rightwards harpoon with barb upwards on top space equals space stack O M with rightwards harpoon with barb upwards on top space plus space stack M P with rightwards harpoon with barb upwards on top space

space space space space equals space stack O M with rightwards harpoon with barb upwards on top space plus space stack O N with rightwards harpoon with barb upwards on top 

Here, vectors OM and ON are mutually perpendicular to each other. Therefore, the  vectors OM and ON are called rectangular components of vector R.

Now, using appropriate notations, X and Y components are represented by straight R with rightwards harpoon with barb upwards on top subscript x space a n d space R with rightwards harpoon with barb upwards on top subscript y, respectively.  

The internationally accepted notations for unit vectors along X-axis and Y-axis are straight i with hat on top space a n d space j with hat on top respectively. Thus, 
straight R with rightwards harpoon with barb upwards on top space equals space R with rightwards harpoon with barb upwards on top subscript x space plus space R with rightwards harpoon with barb upwards on top subscript y space equals space R with rightwards harpoon with barb upwards on top subscript x stack i space with hat on top space plus space R with rightwards harpoon with barb upwards on top subscript y j with hat on top space 
If the vector straight R with rightwards harpoon with barb upwards on top has magnitude R, and makes an angle straight theta with positive direction of X-axis. The from increment OMP comma 
OM space equals space straight R subscript straight x space equals space straight R space cos space straight theta
MP space equals space straight R subscript straight y space equals space straight R space sin space straight theta

Thus comma space straight R with rightwards harpoon with barb upwards on top space equals space straight R subscript straight x straight i with hat on top space plus space straight R subscript straight y straight j with hat on top space equals space straight R space cos space straight theta space straight i with hat on top space plus space straight R space sinθ stack space straight j with hat on top

This is how we resolve the rectangular components of a vector in a plane.