Question

Two equal forces ($P$ each) act at a point inclined to each other at an angle of ${120}^0$. The magnitude of their resultant is:

• A. $P/2$
• B. $P/4$
• C. $P$
• D. $2P$

Answer 1

Answer: (C)

$P$

The magnitude of resultant of two vectors is given by:

$R=\sqrt{A^2+B^2+2ABcos\theta }$ where $\theta$ is the angle between two vectors.

Hence, in this case:

$R=\sqrt{P^2+P^2+2P^{2}cos120}=\sqrt{P^2+P^2+2P^2(-0.5)}=P$