Question

Resultant of two vectors of magnitude `P` and `Q` is of magnitude `Q`.If the magnitude of `vecQ` is doubled now the angle made by new resultant with `vecP` is
A. `30^(@)`
B. `90^(@)`
C. `60^(@)`
D. `120^(@)`

Answer 1

Correct Answer - B
`Q^(2)=P^(2)+Q^(2)+2PQcos theta` ,
`costheta=-P/(2Q),Tan alpha=(2Q sin theta)/(P+2Q cos theta)`