Pressure

Question 1

The following is designed to give a reading of absolute pressure (true or false):

Mercury sphygmomanometer

Answer 1

False. Clinical measurements are expressed as gauge pressures relative to atmospheric pressure.

Question 2

The following is designed to give a reading of absolute pressure (true or false):

Central venous pressure monitor

Answer 2

False. Clinical measurements are expressed as gauge pressures relative to atmospheric pressure.

Question 3

The following is designed to give a reading of absolute pressure (true or false):

Theatre barometer

Answer 3

True. A theatre barometer is designed to measure atmospheric pressure and therefore gives a reading of absolute pressure.

Question 4

The following is designed to give a reading of absolute pressure (true or false):

Pressure altimeter

Answer 4

True. A pressure altimeter measures altitude by measuring the fall in atmospheric pressure with altitude. It therefore expresses absolute pressure.

Question 5

The following is designed to give a reading of absolute pressure (true or false):

Bourdon gauge on a gas cylinder

Answer 5

False. Cylinder pressures are expressed as gauge pressures, such that when the cylinder is empty the gauge will read zero, despite being at atmospheric pressure.

Question 6

The following pressure reading is approximately equal in magnitude to 1 bar (true or false):

1020 cm H2O

Answer 6

True. 1 kPa = 10.2 cm H20. Therefore, 1020 cm H20 = 100 kPa = 1 bar.

Question 7

The following pressure reading is approximately equal in magnitude to 1 bar (true or false):

100 N/m2 (squared)

Answer 7

False. 1 N/m2 = 1 Pa. Therefore, 100 N/m2 = 100 Pa. However, 1 bar = 100 kPa.

Question 8

The following pressure reading is approximately equal in magnitude to 1 bar (true or false):

1 atm

Answer 8

True. 1 atm = 1 bar, which approximately equals atmospheric pressure.

Question 9

The following pressure reading is approximately equal in magnitude to 1 bar (true or false):

75 cm Hg

Answer 9

True. 1 kPa = 7.5 mm Hg = 0.75 cm Hg. Therefore, 75 cm Hg = 100 kPa = 1 bar.

Question 10

The following pressure reading is approximately equal in magnitude to 1 bar (true or false):

100 Pa

Answer 10

False. 100 kPa = 1 bar.

Question 11

Regarding pressure (true or false):

The SI unit for pressure is the bar

Answer 11

False. The SI unit for pressure is the Pascal (Pa).

Question 11

Regarding pressure (true or false):

As a given force is spread over a greater area, pressure rises

Answer 11

False. Pressure = force/area; therefore, as area increases, pressure will fall.

Question 12

Regarding pressure (true or false):

A closed-ended manometer will give an absolute pressure reading

Answer 12

True. Closed-ended manometers have a vacuum as the reference pressure.

Question 13

Regarding pressure (true or false):

An example of an open-ended manometer is the theatre barometer

Answer 13

False. The theatre barometer is a closed-ended manometer.

Question 14

Regarding pressure (true or false):

A manometer is an example of an aneroid gauge

Answer 14

False. A manometer is a liquid-filled tube; an aneroid gauge, by definition, contains no liquid.