Two forces $3\,N$ and $2\, N$ are at an angle $\theta$ such that the resultant is $R$. The first force is now increased to $ 6\,N$ and the resultant become $2R$. The value of is ....... $^o$
Two forces $3\,N$ and $2\, N$ are at an angle $\theta$ such that the resultant is $R$. The first force is now increased to $ 6\,N$ and the resultant become $2R$. The value of is ....... $^o$
$30$
$60$
$90$
$120$
Two forces $3\,N$ and $2\, N$ are at an angle $\theta$ such that the resultant is $R$. The first force is now increased to $ 6\,N$ and the resultant become $2R$. The value of is ....... $^o$
$A = 3N$, $B = 2N$ then $R = \sqrt {{A^2} + {B^2} + 2AB\cos \theta } $
$R = \sqrt {9 + 4 + 12\cos \theta } $ …$(i)$
Now $A = 6N$, $B = 2N$ then
$2R = \sqrt {36 + 4 + 24\cos \theta } $ …$(ii)$
from $(i)$ and $(ii)$ we get $\cos \theta = - \frac{1}{2}$
$\therefore $ $\theta = 120^\circ $
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