Final answer:
The pressure on a piston of larger area in a simple hydraulic device where a pressure of 20 kPa is applied to one piston will remain the same 20 kPa, in accordance with Pascal's Principle.
Step-by-step explanation:
If a pressure of 20 kPa is applied to one piston in a simple hydraulic device, according to Pascal's Principle, the pressure on a piston of larger area will be the same, which is 20 kPa. This is because Pascal’s Principle states that the pressure exerted by a fluid in an enclosed space is transmitted undiminished in all directions within the fluid and to the surfaces of its container. Therefore, even if one piston has a larger area than the other, the pressure remains constant across the system if the pistons are at the same vertical height and the system is frictionless.
In hydraulic systems, it is the force that can be increased by using a larger area piston, not the pressure. For instance, if a 100-N force is applied to a piston, and the connected piston has an area five times greater, the output force would indeed be 500 N, although the pressure remains unchanged.