Air flows through a venture and into atmosphere. Air density is r; atmospheric pressure is ‘Pa’; throat diameter is ‘Dt’; exit diameter is D and exit velocity is ‘U’. The throat is connected to a cylinder containing a frictionless piston attached to a spring. The spring constant is ‘k’. The bottom surface of the piston is exposed to atmosphere. Due to the flow, the piston moves by distance ‘x’. Assuming incompressible frictionless flow, then ‘x’ is
