Question

Three forces of magnitudes $30,60$ and $P$ Newton acting at a point are in equilibrium. If the angle between the first two is ${60}^o$, the value of $P$ is:

• A. $25\sqrt{2}$
• B. $30\sqrt{3}$
• C. $30\sqrt{6}$
• D. $30\sqrt{7}$

Answer 1

The correct option is D $30\sqrt{7}$

• For equilibrium the third force should be equal to resultant of other two.
• so $P=\sqrt[2]{2{30}^2+{60}^2+2\times 30\times 60\times cos{60}^0}$ or $P=79.37Newton$ or $P=30\sqrt[2]{27}$ Newton. Option D is correct.