Question

Solve this:
The resultant of two forces vectors having magnitude 3N and 2N is R. If the first force is doubled, then the resultant is also doubled. The angle between the two given forces:
(1) 30^o
(2) 60^o
(3) 120^o
(4) 150^o

Answer 1

Dear Student,


$$\begin{gathered} lettheanglebe\theta \\ \left(R^2=9+4+12\cos \theta \right)\times 4 \\ now3becomes6NandRto2R \\ 4R^2=36+4+24\cos \theta \\ 4R^2=36+16+48\cos \theta \\ subtracttheaboveeqn \\ 24\cos \theta =-12 \\ \cos \theta =-\frac{1}{2} \\ \theta =120degree \\ Regatrds \end{gathered}$$