Definition: A cubic inch per second (in3/s) is a unit of volumetric flow rate representing one cubic inch of substance passing a point in one second. It measures small to medium volumes, particularly in engineering contexts.

History/origin: The cubic inch is a unit of volume in the imperial and US customary systems of measurement. 'Per second' signifies the rate of flow. It is primarily used in the US, where imperial units are still prevalent.

Current use: In3/s is used in mechanical engineering (e.g., measuring the flow of hydraulic fluids), in the design of engines and pumps, and in other industrial applications where smaller fluid volumes are handled. It is frequently used when measuring the flow of fluids in car engines.