Final answer:
The question regarding the inner diameter of the copper pipe cannot be answered without additional information. However, the related physics questions involve understanding the principles of fluid dynamics and the properties of concave mirrors.
Step-by-step explanation:
The question posed does not provide enough information to determine the inner diameter of the copper pipe with an outer diameter of 40 mm. However, the fluid dynamics-related questions seem to concern physics, specifically, principles related to pressure, fluid flow, and the properties of concave mirrors. For instance, if placing a fluid-carrying pipe in front of a concave mirror at the mirror's focal point, the radius of curvature of the mirror would be twice the distance from the mirror to the pipe, meaning 80 cm in this case. When considering fluid flow through a tapered pipe or a pipe with varying elevation, concepts from Bernoulli's equation and fluid mechanics are applied to determine the necessary gauge pressure or the resultant pressure changes in the system. Copper wire electrical properties are determined using its dimensions and physical constants to calculate resistance, current, and the effects of forces on material elongation.