The resultant of two vectors →P and →Q is →R. If →Q is doubled then the new resultant vector is perpendicular to →P. Then magnitude of →R is:
→R=→P+→Q,→R′=→P+2→Q
∵→R′.→P=0∴(→P+2→Q).→P=0⇒P2+2→Q.→P=0
R2=P2+Q2+2→P.→Q=P2+Q2−P2=Q2⇒R=Q.
The resultant of two vectors →P and →Q is →R. If Q is doubled, the new resultant is perpendicular to P. Then R equals