Final answer:
To establish the required traction force for a Russell traction apparatus, the arrangement of pulleys can be modified to create a mechanical advantage that increases the force without altering the weight. Frictionless pulleys change the force directions without altering magnitudes, allowing the setup to amplify the force exerted along the bone.
Step-by-step explanation:
When setting up a Russell traction apparatus for a patient with a fractured thigh, the force exerted along the leg is crucial for proper healing. If we want to maintain a traction force of 25 N using the same weight, we can adjust the system of pulleys. In a standard traction setup with pulleys, the pulleys redirect the force exerted by a weight. By using a frictionless pulley system, the direction of the weight's force is changed but not its magnitude. Hence, to increase the force along a bone like the tibia or femur without changing the weight, you would need to rearrange the pulleys to create a mechanical advantage.
For instance, using a system where the weight is attached to a rope that runs over a pulley attached to the end of the bed and then connects to the traction system, the force along the bone would be roughly equal to the weight. To amplify this force, additional pulleys could be added to create a compound pulley system, effectively multiplying the original force.
To calculate the required weight () for the traction force, we would balance the traction force with the force due to the weight, considering the mechanical advantage of the pulley system. However, without a specific pulley setup and without more information about friction or additional forces, the precise value of cannot be determined from the provided information.