Final answer:
The question pertains to calculating the average force exerted on an internal part of a rifle that helps reduce recoil. However, without additional data such as the mass and recoil velocity of the internal part, we cannot provide a numerical answer. More information is needed to solve this physics problem.
Step-by-step explanation:
The student's question revolves around the concept of recoil in firearms and the mechanism by which military rifles mitigate these forces. The primary goal of having a mechanism that allows internal parts to recoil over a larger distance is to reduce the average force exerted on the shooter by spreading the deceleration over a longer time.
To answer part (b) of the question, we need to calculate the average force exerted upon the internal part by the gun when it's stopped over a distance of 20.0 cm.
This can be calculated using the work-energy principle or the impulse-momentum theorem. However, as the question does not provide the velocity of the internal part or any other necessary values to calculate it, we cannot directly calculate the average force exerted. Typically, the average force would be found by dividing the change in momentum of the recoiling part by the time interval over which it was stopped, or by dividing the work done to stop it by the distance. Without additional data, such as the mass of the internal part and its recoil velocity, we cannot provide a numerical answer.
For a comprehensive understanding, we would require additional specifics regarding the internal part's mass and its velocity upon recoil, which are not provided in the question. Consequently, it's essential to gather all relevant data to solve physics problems effectively.