Suppose the tension in cord is T and it makes an angle a with horizontal. Tension T is resolved in horizontal and vertical components. T cos α is horizontal component and T sin α is vertical component. Horizontal components T cos α balance each other while vertical components T sin α add up and provide net vertical force 2T sin α which balances the weight W = 8kg-wt.
\(\therefore \ 2T\sin\alpha = W\)
or \(T = \frac{W}{2\sin\alpha}\)
For cord to be completely horizontal, α = 0°
\(\therefore\ sin \ \alpha = sin\ 0^\circ = 0\)
Hence \(T = \frac{W}{0} = \infty\) (infinite) which is not possible.
Therefore horizontal tension can not balance vertical weight.
