a uniform bar AB is 4m long and weights of 10kg and 20kg hanging at 1m and 3m from the end.if it remains horizontal over a knife edge balances at a point 1.75m from B ,what is the weight of the bar

Dear Student,

Please find below the solution to the asked query:

Let W is the weight of the bar. This acts from the middle point of the bar.

$$\begin{gathered} Here, we have to consider the torque about the knife edge. \\ 10g\times 1.25+mg\times 0.25=20g\times 0.75 \\ \Rightarrow 125+2.5 m=150\Rightarrow 2.5 m=25\Rightarrow m=10 kg \end{gathered}$$

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