Final answer:
The true statement about fluid power is that fluid power systems use either a liquid or a gas to generate, control, and transmit power. Hydraulic systems, which use liquids, can multiply force thanks to the properties of fluid mechanics, and power in fluid systems is also dependent on material strength and other factors, such as efficiency and operating conditions.
Step-by-step explanation:
The statement that is true about fluid power is: A. A fluid power system uses either a liquid or a gas to generate, control, and transmit power. Fluid power is a critical concept in mechanical and civil engineering, which deals with the use of fluids to transmit energy. When we consider Bernoulli's equation, we see the relationship between velocity, pressure, and elevation in determining fluid flow and hence, power.
Hydraulic systems are one example where power capacity is a function of the applied pressure and the size of the piston. Due to Pascal's principle, *pressure* applied to an enclosed fluid is transmitted undiminished throughout the fluid, allowing for force multiplication, much like mechanical levers. This can be seen in typical hydraulic systems with two fluid-filled cylinders connected by a tube. Applying force to one piston creates pressure that is transmitted through the fluid, exerting an increased force through a larger area on the opposing piston.
The statement D. Hydraulics uses liquids whereas pneumatics uses gases is also true but is more of a differentiation within fluid power systems rather than a fundamental truth of fluid power itself. Liquids are generally used in hydraulic systems for their incompressibility, which allows for precise control of movement, while gases are used in pneumatic systems due to their compressibility, which allows for a cushioning effect and quick but less precise movement.
It's important to note that while the power capacity of fluid systems is dependent on the physical strength of the materials used, the practical limits are also influenced by other factors such as the efficiency of the system components, the type of fluid used, and the operating conditions.