What is the pressure in the line between a hand pump and an actuating cylinder if the hand pump builds up a pressure of 100 PSI?

In a hydraulic system, when a hand pump builds up pressure, that pressure is transmitted throughout the fluid in the system. If the hand pump is effectively functioning and there are no significant leaks or pressure drops within the system, the pressure in the line between the hand pump and the actuating cylinder will equal the pressure developed by the pump itself.

In this scenario, since the hand pump creates a pressure of 100 PSI, this pressure will be the same at any point in the line up to the actuating cylinder, assuming the system is closed and there are no losses due to friction, elevation changes, or leaks. Therefore, the pressure in the line between the hand pump and the actuating cylinder remains at 100 PSI.

This principle is fundamental in fluid mechanics and hydraulic systems, where the pressure applied in one part of the system is transmitted uniformly throughout the incompressible fluid. Thus, the correct answer is that the pressure in the line is indeed 100 PSI.