Practice portal › Laws of Motion › Equilibrium of Concurrent Forces
Asked in JEE Main 25th July 1st Shift 2022 · Three or more forces in balance
Idea: equilibrium means the components balance in each direction separately. Take the vertical as the reference, since both slanting forces sit at 45° to it.
Measuring x to the right and y upward, and using sin 45°=cos 45°=1/(√2):
the 2 N force, up and to the left, is (-√2, +√2);
the 1 N force, up and to the right, is (+1/(√2), +1/(√2));
F₁ is (+F₁, 0) and F₂ is (0, -F₂).
Horizontal: -√2+1/(√2)+F₁=0, so
F₁=√2-1/(√2)=(2-1)/(√2)=1/(√2).
Vertical: √2+1/(√2)-F₂=0, so
F₂=(2+1)/(√2)=3/(√2).
(F₁)/(F₂)=(1/√2)/(3/√2)=1/3, so x=3.
The √2 cancels in the ratio, which is why the answer is a whole number.
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