For the system to be balanced, the torque generated on each side of the fulcrum must be the same.
On the other hand, the torque τ generated by a force F applied at a distance d from the fulcrum is given by the equation:
[tex]\tau=d\times F[/tex]Let W be the weight of the rock. Since the torque generated by the crate must be the same as the torque generated by the rock, then:
[tex](5.4m)\times(800N)=(730\operatorname{cm})\times W[/tex]Rewrite the distance of 730 cm in meters:
[tex]\Rightarrow(5.4m)\times(800N)=(7.30m)\times W[/tex]Solve for W to find the weight of the rock:
[tex]\Rightarrow W=\frac{5.4m\times800N}{7.30m}=591.78\ldots N\approx592N[/tex]Therefore, the rock must be as large as for its weight to be equal to 592N.
