Question

The gauge pressure of a pneumatic cylinder reads 20 lb/in.² when the volume is 30 in.³. The cylinder is compressed until the gauge reads 60 lb/in.². What is the absolute pressure before the cylinder gas is compressed?

Answer 1

Circle ⭕️
Yes
The answers are circled

Answer 2

The absolute pressure before the cylinder gas is compressed is 34.696 lb/in.²

Step-by-step explanation:

The Initial pressure, P₁ of the pneumatic cylinder = 20 lb/in.² gauge

Initial volume, V₁ of the cylinder = 30 in.³

Final pressure. P₂ of the pneumatic cylinder = 60 lb/in.²gauge

Gauge pressure = Absolute pressure - Atmospheric pressure, P
`_(atm)`

∴ Absolute pressure = Gauge pressure + Atmospheric pressure

The absolute pressure before the cylinder gas is compressed is found as follows;

Initial absolute pressure of gas in the cylinder = P₁ + P
`_(atm)`

Where Atmospheric pressure, P
`_(atm)` = 14.696 lb/in.²

Initial absolute pressure of gas in the cylinder = 20 lb/in.² + 14.696 lb/in.² = 34.696 lb/in.²

Hence the absolute pressure before the cylinder gas is compressed = 34.696 lb/in.².