Final answer:
The question is about physics, specifically torque balance and equilibrium. One must calculate the torque from gravitational forces acting on the masses and ensure these sum to zero for equilibrium. For unknown masses, set the clockwise and counterclockwise torques equal to find the value.
Step-by-step explanation:
The question involves concepts of physics related to torque balance and the equilibrium of forces. When dealing with a system like a rod with weights, a fulcrum, and different arms, the objective is to make sure that the sum of torques around the pivot point (fulcrum) is zero to achieve equilibrium.
This can involve calculations using the torques produced by the gravitational forces acting on the masses at specified distances from the fulcrum.
For instance, if you're given a thin rod with masses attached at different points, you would calculate the torque due to each mass relative to the pivot point, considering the force of gravity acting on each mass (which is mass times the acceleration due to gravity) and the perpendicular distance from the pivot point to the line of action of each force.
The torques acting in the clockwise and counterclockwise directions need to balance out for the rod to be in equilibrium.
If the problem is to find an unknown mass that balances the system, you would set up an equation where the sum of the clockwise torques equals the sum of the counterclockwise torques and solve for the unknown mass.
Similarly, finding the normal reaction force at the fulcrum when the system is balanced involves summing up the forces acting on the system and setting them equal to the normal force, taking into account that the system does not accelerate (Newton's second law).