A pneumatic system uses a(n) __________ to provide power.

In a pneumatic system, power is provided through the use of gas, specifically compressed air. Pneumatic systems utilize the energy stored in compressed air to create motion and perform work. This mechanism takes advantage of the properties of gases, which can be compressed to store energy and then released to drive pistons, actuators, or other mechanical components.

The use of gas is particularly advantageous in applications requiring quick responses and high-speed operations, as the compressibility of gases allows for rapid changes in pressure and volume. This differentiates pneumatic systems from hydraulic systems, which rely on liquids, or electric systems that depend on electrical current for powering devices. The choice of gas is fundamental to the performance and design of pneumatic equipment, making it the correct answer for this question.