The component of a vector `r` along X-axis will have maximum value if

Options

A. `r` is along positive Y-axis
B. `r` is along positve X-axis
C. `r` makes an angle of `45^(@)` with the X-axis
D. `r` is along negative Y-axis.

Answer

B

Explanation

Let `r` makes an angle `theta` with positive x-axis component of r along X-axis
`r_(x)=|r|cos theta`
`(r_(x))_(maxim u m)=|r|(cos theta)_(maxim um)`
`r_(x)=|r| cos theta`
`=|r| cos 0^(@)=|r| ( :. cos theta "is maxim u m of" theta= 0^(@))`
As `theta=0^(@)`
`r` is along positive x-axis