High School

A vacuum gauge connected to a chamber reads 35 kPa at a location where the atmospheric pressure is 92 kPa. Determine the absolute pressure in the chamber.

a. 52 kPa
b. 25 kPa
c. 57 kPa
d. 75 kPa
e. 95 kPa

Answer :

c. 57 kPa is the absolute pressure in the chamber.

To find the absolute pressure in the chamber, we need to understand the relationship between gauge pressure and absolute pressure. Absolute pressure is calculated by adding the atmospheric pressure to the gauge pressure (or subtracting in the case of a vacuum gauge).

Given:

  • Gauge Pressure (vacuum): 35 kPa
  • Atmospheric Pressure: 92 kPa

Because the gauge pressure is measuring a vacuum, it means it’s below atmospheric pressure by 35 kPa. So, we subtract this value from the atmospheric pressure to find the absolute pressure:

  • Absolute Pressure = Atmospheric Pressure - Gauge Pressure = 92 kPa - 35 kPa = 57 kPa

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