`O` is the centre of an equilateral triangle `ABC`. `F_(1), F_(2)` and `F_(3)` are the three forces acting along the sides `AB, BC` and `AC` respectively. What should be the value of `F_(3)` so that the total torque about `O` is zero?

Options

A. `(F_1 + F_2)`
B. `(F_1 + F_2)/(2)`
C. `F_1 - F_2`
D. `F_1 + F_2`

Answer

D

Explanation

(d) The torque `F_1 d` and `F_2 d` of `F_1` and `F_2` respectively are counter-clockwise. The torque `F_3 d` is clockwise. Applying condition for rotational equilibrium,
`F_1 d + F_2 d - F_3 d = 0` or `F_3 = F_1 + F_2`.
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