HBO CHT EXAM 2025 QUESTIONS AND
ANSWERS
Pressure is defined as? - ANS The force per unit area acting on a surface in a direction
perpendicular to that surface
Force is defined as? - ANS An External cause responsible for any change of physical system.
Acceleration is defined as? - ANS The rate of change (or time derivative) of velocity.
Gas is defined as? - ANS A phase of matter
Solid is defined as? - ANS A liquid that is at its freezing point.
Plasma is defined as? - ANS Atoms or molecules that have become ionized.
Liquid is defined as? - ANS A solid that is at its melting point
In the gas phase, the atoms or molecules basically move? - ANS Randomly
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, Liquids change to a gas at? - ANS Their respective boiling points! Think about water turning
to steam when it boils
When applying pressure to a fluid, the pressure is exerted? - ANS In all directions equally.
(pascal's law)
Hydraulics is a branch of science and engineering concerned with the mechanical properties of?
- ANS Liquids! Pneumatic refers to gas fyi
A mechanical gauge is used when measuring gas pressure in a sealed container. For all common
pressure gauges, the pressure indicated on the gauge is? - ANS Less than the absolute
pressure (Gauges (and gauge pressures) ignore the ambient (barometric) pressure around us.
Absolute pressure can be defined as? - ANS The amount of pressure within the sealed vessel
+ the amount of pressure outside the sealed vessel.
Gauge pressure? - ANS The amount of pressure within the sealed vessel only
Ambient pressure? - ANS The amount of pressure outside of the sealed vessel only.
Absolute pressure can be defined as? - ANS Gauge pressure + atmospheric pressure, Total
pressure, True pressure
1 Atm worth of pressure? - ANS 760 mmHg, 14.7 PSI, 33 FSW
Barometric pressure in Denver, CO (elevation 5000 ft) is less than barometric pressure at sea
level true or false? - ANS True
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, To Convert from ATA to mmHg - ANS Multiply by 760
To Convert from ATA to FSW - ANS Subtract 1, then multiply by 33
To convert from ATA to PSI - ANS Subtract 1, then multiply by 14.7
To convert from FSW to ATA - ANS Divide by 33, then add 1
To convert from FSW to ATA - ANS Add 33, then divide by 33
To convert from PSI to ATA - ANS Divide by 14.7, then add 1
To convert from PSI to ATA - ANS Add 14.7, then divide by 14.7
To convert from mmHg to ATA - ANS Divide by 760
To convert from PSIG to PSIA - ANS Add 14.7, PSIG means "pound per square inch gauge".
PSIA means pounds per square ince absolute.
Boyle's law is about the? - ANS Pressure-volume relationship. Boyle's law says that with
temperature constant, the volume of a gas is inversely proportional to the pressure.
According to Boyle's Law, (assuming the temperature remains constant) when the pressure
increases, the volume? - ANS Decreases proportionally
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When applying Boyle's law to the human body, we worry about air-filled spaces being shrunk (
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or squeezed) when pressure around the body increases. This is known as? - ANS Barotrauma
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ANSWERS
Pressure is defined as? - ANS The force per unit area acting on a surface in a direction
perpendicular to that surface
Force is defined as? - ANS An External cause responsible for any change of physical system.
Acceleration is defined as? - ANS The rate of change (or time derivative) of velocity.
Gas is defined as? - ANS A phase of matter
Solid is defined as? - ANS A liquid that is at its freezing point.
Plasma is defined as? - ANS Atoms or molecules that have become ionized.
Liquid is defined as? - ANS A solid that is at its melting point
In the gas phase, the atoms or molecules basically move? - ANS Randomly
1
Page
@COPYRIGHT SIRJOEL 2025/2026
, Liquids change to a gas at? - ANS Their respective boiling points! Think about water turning
to steam when it boils
When applying pressure to a fluid, the pressure is exerted? - ANS In all directions equally.
(pascal's law)
Hydraulics is a branch of science and engineering concerned with the mechanical properties of?
- ANS Liquids! Pneumatic refers to gas fyi
A mechanical gauge is used when measuring gas pressure in a sealed container. For all common
pressure gauges, the pressure indicated on the gauge is? - ANS Less than the absolute
pressure (Gauges (and gauge pressures) ignore the ambient (barometric) pressure around us.
Absolute pressure can be defined as? - ANS The amount of pressure within the sealed vessel
+ the amount of pressure outside the sealed vessel.
Gauge pressure? - ANS The amount of pressure within the sealed vessel only
Ambient pressure? - ANS The amount of pressure outside of the sealed vessel only.
Absolute pressure can be defined as? - ANS Gauge pressure + atmospheric pressure, Total
pressure, True pressure
1 Atm worth of pressure? - ANS 760 mmHg, 14.7 PSI, 33 FSW
Barometric pressure in Denver, CO (elevation 5000 ft) is less than barometric pressure at sea
level true or false? - ANS True
2
Page
@COPYRIGHT SIRJOEL 2025/2026
, To Convert from ATA to mmHg - ANS Multiply by 760
To Convert from ATA to FSW - ANS Subtract 1, then multiply by 33
To convert from ATA to PSI - ANS Subtract 1, then multiply by 14.7
To convert from FSW to ATA - ANS Divide by 33, then add 1
To convert from FSW to ATA - ANS Add 33, then divide by 33
To convert from PSI to ATA - ANS Divide by 14.7, then add 1
To convert from PSI to ATA - ANS Add 14.7, then divide by 14.7
To convert from mmHg to ATA - ANS Divide by 760
To convert from PSIG to PSIA - ANS Add 14.7, PSIG means "pound per square inch gauge".
PSIA means pounds per square ince absolute.
Boyle's law is about the? - ANS Pressure-volume relationship. Boyle's law says that with
temperature constant, the volume of a gas is inversely proportional to the pressure.
According to Boyle's Law, (assuming the temperature remains constant) when the pressure
increases, the volume? - ANS Decreases proportionally
3
When applying Boyle's law to the human body, we worry about air-filled spaces being shrunk (
Page
or squeezed) when pressure around the body increases. This is known as? - ANS Barotrauma
@COPYRIGHT SIRJOEL 2025/2026
