What is the difference between absolute pressure and gauge pressure?

Gauge pressure is measured against the surrounding atmosphere, so an ordinary pressure gauge reads zero when it is open to the air even though real pressure is acting on it. Absolute pressure is measured from a perfect vacuum, so it equals the gauge reading plus atmospheric pressure, about 14.7 psi at sea level. Gas law calculations use absolute pressure.

What does specific gravity actually compare?

For a liquid or a solid, specific gravity compares the density of that substance to the density of pure water. Because it is a density divided by a density, the units cancel and the result is a pure number with no unit attached. A value above one means the substance is denser than water, and a value below one means it is less dense.

How do I tell conduction, convection, and radiation apart?

Conduction moves heat through direct contact within or between materials, as when a hot cylinder heats the fins bolted to it. Convection moves heat by the bulk motion of a fluid, so warmed air or oil physically carries energy from one place to another. Radiation needs no medium at all and travels as electromagnetic waves, which is how the sun heats a ramp.

What does Bernoulli's principle say for the written test?

For a fluid moving through a tube or duct, an increase in velocity is accompanied by a decrease in static pressure, and a decrease in velocity brings static pressure back up. That is why static pressure drops at the narrow throat of a venturi where the flow speeds up. On the test, the correct answer for rising velocity is falling static pressure.

Do I have to memorize formulas for this area?

Only a short list. Know that absolute pressure equals gauge plus atmospheric, that work equals force times distance and power is work divided by time, that mechanical advantage is resistance divided by effort, and the basic gas law relationships. Most questions test whether you know which quantity rises when another falls, not whether you can grind through a long calculation.

What is the relationship between absolute pressure, gauge pressure, and atmospheric pressure?

Absolute pressure equals atmospheric pressure minus gauge pressure

Absolute pressure equals gauge pressure minus atmospheric pressure

Which statement correctly describes the heat transfer method known as convection?

Heat transfer by the circulation of a heated fluid or gas

Heat transfer by electromagnetic waves through space

Heat transfer through direct contact between two solids

A first-class lever provides a mechanical advantage when the

effort arm is longer than the resistance arm

effort arm equals the resistance arm

effort arm is shorter than the resistance arm

What does the specific gravity of a substance compare?

The density of the substance to the density of water

The volume of the substance to its mass

The weight of the substance to its volume

What is the mass number of an element?

The number of protons and neutrons.

The number of protons and electrons.

The number of electrons and neutrons.

What is formed when two molecules of hydrogen combine with one molecule of oxygen?

Two molecules of hydrogen peroxide (2H2O2).

One molecule of hydrogen peroxide (H2O2).

What is the atomic number of an element?

The number of protons in the atom.

The number of neutrons in the atom.

The number of electrons in the atom.

protons, neutrons, and electrons.

photons, protons, and electrons.

neutrons, photons, and electrons.

As the electron shells in an atom get further from the nucleus, the spacing between successive shells

increases, so the shells get further apart.

decreases, so the shells crowd closer together.

collapses, so the shells merge into one.

The atomic mass of an atom is the

number of protons plus the number of neutrons.

number of neutrons plus the number of electrons.

number of electrons plus the number of protons.

A positive ion is an atom that

is missing one or more electrons.

has gained one or more electrons.

An atom is made up of which three basic particles?

Protons, neutrons, and electrons.

Protons, electrons, and positrons.

Electrons, positrons, and neutrons.

Physics for Aviation — FAA A&P Test Questions (ACS AM.I.J)

Physics for Aviation is the block of the General written test that feels like a high school science class, and that is exactly how it is tested. The questions are broad but shallow: define a term, state a law, pick the correct relationship, or work a one-step ratio. You are not asked to derive anything. What trips candidates up is not the difficulty of the physics but the precision of the wording, because most distractors are built by reversing a relationship or swapping one unit for another. Learn the definitions cleanly and this area pays back quickly.

Written by the AMTprep editorial team · Published July 27, 2026 · Last reviewed October 21, 2026

Written against the FAA primary sources cited at the foot of this page.

What ACS AM.I.J covers

The physics material in FAA-H-8083-30 supplies nearly every question in this area, and it is wide but shallow. Matter, the states of matter, density, specific gravity, and thermal expansion come first: specific gravity compares the density of a substance to the density of water for liquids and solids, which is why it is a plain ratio with no units and why a hydrometer reading tells you something useful about battery electrolyte. Most solids, liquids, and gases expand when heated, which is the basis for several questions. Pressure follows: absolute pressure equals gauge pressure plus atmospheric pressure, a gauge reads zero when it is simply open to the atmosphere, and the gas laws tie pressure, volume, and temperature together. Boyle's law holds temperature constant, so compressing a confined gas into a smaller volume raises its pressure; Charles's law holds pressure constant; the general gas law combines the two. Heat questions ask you to separate conduction, convection, and radiation, with convection being heat carried by the bulk movement of a fluid, whether that fluid is air, water, or oil. Mechanics covers Newton's three laws, work, power, force, and the simple machines: levers of all three classes, pulleys, gears, and inclined planes, with mechanical advantage found from the ratio of resistance to effort or from the ratio of the arms. Fluids and basic aerodynamics close the area out, including Pascal's law, the venturi, and Bernoulli's principle, where static pressure falls as the velocity of a fluid rises.

Where this sits on the test

ACS AM.I.J is tested on the FAA General written test, one of 1,553 ACS-tagged questions in the General bank. Every question tagged to this area carries a worked rationale and its FAA handbook reference, so you can drill the code itself rather than the whole test.

FAA handbook references

FAA-H-8083-30

Three traps candidates fall into

Gas law problems get worked in Fahrenheit or Celsius. Boyle's law, Charles's law, and the general gas law all require an absolute temperature scale, so convert to Rankine by adding about 460 to degrees Fahrenheit, or to Kelvin by adding about 273 to degrees Celsius, before the ratio means anything.
Gauge and absolute pressure get treated as the same number. A gauge reads only the pressure above the surrounding atmosphere, so it sits at zero at rest at sea level, while absolute pressure is that reading plus roughly 14.7 psi. Gas law work needs the absolute value, not the gauge value.
Every first-class lever is assumed to multiply force. A first-class lever gives a mechanical advantage greater than one only when the fulcrum is closer to the resistance than to the effort, making the effort arm the longer one. Move the fulcrum the other way and the same lever multiplies distance instead.

50 free sample questions from ACS AM.I.J

AM.I.JTap an answer
What is the relationship between absolute pressure, gauge pressure, and atmospheric pressure?
Show the answer and explanation
Answer: Absolute pressure equals gauge pressure plus atmospheric pressure
Why: Gauge pressure is measured relative to ambient atmospheric pressure (a gauge reads zero when open to the atmosphere). To obtain absolute pressure, which is measured from a perfect vacuum, you add the atmospheric pressure to the gauge reading. The handbook's physics chapter defines absolute pressure as gauge pressure plus atmospheric pressure.· FAA-H-8083-30 — Physics, pressure measurement
AM.I.JTap an answer
According to Boyle's law, if the volume of a confined gas is decreased while temperature is held constant, the pressure of the gas will
Show the answer and explanation
Answer: increase
Why: Boyle's law states that, at constant temperature, the pressure of a confined gas is inversely proportional to its volume (P x V = constant). Reducing the volume forces the same number of gas molecules into a smaller space, so they strike the container walls more often, raising the pressure.· FAA-H-8083-30 — Physics, gas laws (Boyle's law)
AM.I.JTap an answer
Which statement correctly describes the heat transfer method known as convection?
Show the answer and explanation
Answer: Heat transfer by the circulation of a heated fluid or gas
Why: Convection is the transfer of heat by the movement of a heated fluid or gas; warmer, less dense fluid rises and cooler fluid moves in to replace it, creating circulation. Conduction is transfer through direct contact, and radiation is transfer by electromagnetic waves, so those describe the other two heat-transfer methods.· FAA-H-8083-30 — Physics, heat transfer
AM.I.JTap an answer
A first-class lever provides a mechanical advantage when the
Show the answer and explanation
Answer: effort arm is longer than the resistance arm
Why: Mechanical advantage of a lever equals the length of the effort arm divided by the length of the resistance arm. When the effort (force) arm is longer than the resistance arm, the ratio exceeds one, so a smaller applied force can move a larger resistance. Equal arms give a ratio of one (no advantage), and a shorter effort arm gives a ratio less than one.· FAA-H-8083-30 — Physics, simple machines (levers)
AM.I.JTap an answer
What does the specific gravity of a substance compare?
Show the answer and explanation
Answer: The density of the substance to the density of water
Why: Specific gravity is the ratio of the density of a substance to the density of pure water, which is the standard reference. Because it is a ratio of two densities, it is a dimensionless number; a value greater than one means the substance is denser than water. Weight divided by volume defines density itself, not specific gravity.· FAA-H-8083-30 — Physics, density and specific gravity
AM.I.JTap an answer
According to Bernoulli's principle, as the velocity of a fluid moving through a tube increases, the static pressure of that fluid
Show the answer and explanation
Answer: decreases
Why: Bernoulli's principle states that within a flowing fluid, an increase in velocity is accompanied by a decrease in static pressure, because the total energy of the flow is conserved. As fluid speeds up through a constriction (a venturi), more of its energy is kinetic and less is in the form of static pressure.· FAA-H-8083-30 — Physics, fluid mechanics (Bernoulli's principle)
AM.I.JTap an answer
Newton's first law of motion states that a body at rest tends to remain at rest, and a body in motion tends to remain in motion, unless acted upon by
Show the answer and explanation
Answer: an external force
Why: Newton's first law, the law of inertia, states that an object will not change its state of motion unless an unbalanced external force acts on it. Inertia is the property by which the body resists this change; it is not something that is lost, and mass does not spontaneously change, so the external force is the only correct cause.· FAA-H-8083-30 — Physics, motion (Newton's laws)
AM.I.JTap an answer
What happens to most solid materials when they are heated?
Show the answer and explanation
Answer: They expand
Why: When most solids are heated, the increased energy causes their molecules to vibrate more and move farther apart, so the material expands in length, area, and volume. This is why mechanics must account for thermal expansion in fitted parts and why different metals with different expansion rates can loosen or bind when temperatures change.· FAA-H-8083-30 — Physics, heat and thermal expansion
AM.I.JTap an answer
On the Fahrenheit temperature scale, water at standard atmospheric pressure boils at
Show the answer and explanation
Answer: 212 degrees
Why: On the Fahrenheit scale at standard sea-level atmospheric pressure, water freezes at 32 degrees and boils at 212 degrees, giving 180 degrees between the two points. The 100-degree value is the boiling point on the Celsius scale, and 32 degrees Fahrenheit is the freezing point of water, not its boiling point.· FAA-H-8083-30 — Physics, temperature scales
AM.I.JTap an answer
Power is best defined as the
Show the answer and explanation
Answer: rate at which work is done
Why: Power is the time rate of doing work, calculated as work divided by the time required to do it. Two machines can perform the same total work, but the one that does it in less time develops more power. Force alone and total work are separate quantities that do not include the element of time.· FAA-H-8083-30 — Physics, work and power
AM.I.JTap an answer
An atom with three electrons in its outer shell is said to be
Show the answer and explanation
Answer: trivalent.
Why: An atom's valency is set by the number of electrons in its outer (valence) shell. With three electrons available to form bonds, the atom is described as trivalent. Two electrons would make it divalent and one would make it univalent. FAA-H-8083-30 covers the physics of matter and atomic structure.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
What is the mass number of an element?
Show the answer and explanation
Answer: The number of protons and neutrons.
Why: The mass number counts the nucleons in the nucleus, which are the protons plus the neutrons. Electrons are far too light to contribute meaningfully and are not counted. FAA-H-8083-30 covers atomic structure and the physics of matter.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
What is formed when two molecules of hydrogen combine with one molecule of oxygen?
Show the answer and explanation
Answer: Two molecules of water (2H2O).
Why: Combining two hydrogen molecules with one oxygen molecule forms two water molecules, written 2H2O. Each water molecule is built from two hydrogen atoms bonded to one oxygen atom. FAA-H-8083-30 covers basic chemistry and the physics of matter.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
Breaking a chemical compound down into its constituent elements is called
Show the answer and explanation
Answer: analysis.
Why: Breaking a compound down into its constituent elements is termed analysis, the opposite of synthesis where elements combine. This separates the compound into simpler parts rather than forming anything new. FAA-H-8083-30 covers basic chemistry and the physics of matter.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
What is the atomic number of an element?
Show the answer and explanation
Answer: The number of protons in the atom.
Why: The atomic number equals the number of protons in the nucleus, and it uniquely fixes which element the atom is. Neutron count varies between isotopes and electron count varies with ionization, so only the proton number defines the atomic number. FAA-H-8083-30 covers atomic structure.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
An atom consists of
Show the answer and explanation
Answer: protons, neutrons, and electrons.
Why: An atom is built from a nucleus of protons and neutrons surrounded by orbiting electrons. Photons and positrons are not structural components of an ordinary atom. FAA-H-8083-30 covers atomic structure and the physics of matter.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
The maximum number of electrons in the innermost shell of an atom is
Show the answer and explanation
Answer: 2.
Why: The innermost (K) shell can hold a maximum of two electrons. Only from the second shell onward can a shell accommodate eight, so two is the correct limit for the inner shell. FAA-H-8083-30 covers atomic structure and electron shells.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
The mass of a proton is approximately equal to the mass of a
Show the answer and explanation
Answer: neutron.
Why: A proton and a neutron have almost identical masses, each about one atomic mass unit, with the neutron only marginally heavier. The electron is roughly 1,800 times lighter. FAA-H-8083-30 covers atomic structure and the physics of matter.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
When the outer shell of an atom is full, the element is
Show the answer and explanation
Answer: practically inert.
Why: An atom whose outer shell is full has no tendency to gain, lose, or share electrons, so it does not readily react or conduct. This stable configuration is why the noble gases are practically inert. FAA-H-8083-30 covers atomic structure and electron shells.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
The attractive force that holds together molecules of the same compound is called
Show the answer and explanation
Answer: cohesion.
Why: Attraction between molecules of the same substance is called cohesion, which holds like molecules together. Adhesion describes attraction between unlike materials. FAA-H-8083-30 covers the physics of matter, including cohesion and adhesion.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
Oxygen has a valency of
Show the answer and explanation
Answer: 2.
Why: Oxygen needs two electrons to complete its outer shell, giving it a valency of two. This is why it bonds with two hydrogen atoms to form water, H2O. FAA-H-8083-30 covers basic chemistry and atomic structure.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
As the electron shells in an atom get further from the nucleus, the spacing between successive shells
Show the answer and explanation
Answer: increases, so the shells get further apart.
Why: As electron shells extend outward from the nucleus, the spacing between successive shells increases. The shells get further apart with distance rather than collapsing or crowding together. FAA-H-8083-30 covers atomic structure and electron shells.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
What determines an element's identity?
Show the answer and explanation
Answer: The number of protons.
Why: An element's identity is determined solely by its proton count, the atomic number. Changing neutrons only produces a different isotope of the same element, and changing electrons only produces an ion. FAA-H-8083-30 covers atomic structure.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
An isotope of an element has a different number of _________ than the common form.
Show the answer and explanation
Answer: neutrons
Why: Isotopes of an element share the same number of protons but differ in their number of neutrons. An isotope therefore has more or fewer neutrons than the common form, which is why its mass differs while its chemical identity does not. FAA-H-8083-30 covers atomic structure and isotopes.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
The smallest part of an element that still retains the chemical properties of that element is
Show the answer and explanation
Answer: an atom.
Why: The atom is the smallest particle of an element that still retains the chemical properties of that element. Subatomic particles such as quarks and mesons no longer behave as the element, so the atom is correct.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
The nucleus of an atom contains
Show the answer and explanation
Answer: protons and neutrons.
Why: The nucleus holds the protons and neutrons, which together account for nearly all of the atom's mass. Electrons orbit outside the nucleus rather than residing within it, so options placing electrons in the nucleus are wrong.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
The atomic mass of an atom is the
Show the answer and explanation
Answer: number of protons plus the number of neutrons.
Why: Atomic mass is the sum of the nucleons in the nucleus, the protons plus the neutrons. Electrons are too light to add appreciably to the mass, so they are not included in the count.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
When ice melts into liquid water, the resulting water takes up
Show the answer and explanation
Answer: less space.
Why: Water is unusual in that ice is less dense than liquid water because the open crystal structure of ice expands its volume. When ice melts, that structure collapses and the resulting water takes up less space.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
Which form of heat is absorbed to change a solid into a liquid?
Show the answer and explanation
Answer: Heat of fusion.
Why: Changing a solid into a liquid requires the latent heat of fusion, the energy absorbed to break the bonds of the solid structure while the temperature stays constant. This is the heat added during melting.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
A change of state directly from a solid to a gas, without passing through the liquid state, is called
Show the answer and explanation
Answer: sublimation.
Why: Sublimation is the direct change of a substance from solid to gas without passing through the liquid phase. Evaporation involves a liquid surface, so it does not describe this solid-to-gas transition.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
A positive ion is an atom that
Show the answer and explanation
Answer: is missing one or more electrons.
Why: A positive ion forms when an atom loses one or more electrons, leaving more protons than electrons and an overall positive charge. Gaining electrons instead would create a negatively charged ion.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
Carbon-14 and carbon-12 are isotopes of carbon, so both atoms have the same
Show the answer and explanation
Answer: number of protons.
Why: Carbon-14 and carbon-12 are isotopes of the same element, so they share the same number of protons. They differ only in neutron count, which gives them different mass numbers while keeping them both carbon.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
If a neutral atom has 2 protons, how many electrons does it have?
Show the answer and explanation
Answer: 2.
Why: A neutral atom has equal numbers of protons and electrons so that the charges balance. With two protons it therefore has two electrons, identifying the atom as helium.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
A molecule made up entirely of identical atoms is a molecule of
Show the answer and explanation
Answer: an element.
Why: A molecule made up of identical atoms is a molecule of an element, since only one type of atom is present. A compound, by contrast, requires two or more different kinds of atom.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
Two or more different elements chemically combined in a single substance form a
Show the answer and explanation
Answer: compound.
Why: When two or more different elements are chemically combined in a single substance, the result is a compound. A mixture does not chemically bond the elements, so compound is the correct term.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
In a neutral atom, the number of protons is equal to the number of
Show the answer and explanation
Answer: electrons.
Why: In a neutral atom the positive and negative charges balance, so the number of protons equals the number of electrons. Positrons and molecules play no part in this balance.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
The electrical charge carried by an electron is
Show the answer and explanation
Answer: negative.
Why: The electron carries a single negative charge, balancing the positive charge of the proton. The neutron is uncharged, so neither positive nor neutral describes the electron.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
A valence electron is an electron located
Show the answer and explanation
Answer: in the outermost shell.
Why: A valence electron is one occupying the outermost shell of an atom. These outer electrons govern how the atom bonds and reacts, which is why inner-shell electrons are not valence electrons.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
The attractive force that holds together molecules of unlike substances is called
Show the answer and explanation
Answer: adhesion.
Why: When unlike atoms or molecules are joined, the attraction between the dissimilar particles is termed adhesion. Cohesion applies to attraction between like molecules of the same substance, so adhesion is correct here.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
Hydrogen, deuterium, and tritium are isotopes of hydrogen that differ from one another in the number of
Show the answer and explanation
Answer: neutrons.
Why: Hydrogen, deuterium, and tritium are isotopes of hydrogen, all with one proton and one electron. They differ only in their neutron count, having zero, one, and two neutrons respectively.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
Anything that has mass and occupies space, whether solid, liquid, or gas, is defined as
Show the answer and explanation
Answer: matter.
Why: Anything that has mass and occupies space, whether solid, liquid, or gas, is defined as matter. Energy has no mass or volume of its own, and volume is only a measure of the space occupied, so matter is correct.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
An atom is made up of which three basic particles?
Show the answer and explanation
Answer: Protons, neutrons, and electrons.
Why: All matter is composed of atoms, and every atom is built from protons and neutrons in a central nucleus with electrons orbiting around it. Positrons are not part of ordinary atomic structure, so any choice that lists them is incorrect.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
The force of molecular attraction between two unlike substances is called
Show the answer and explanation
Answer: adhesion.
Why: Adhesion is the attraction between molecules of two different (unlike) substances, such as a liquid clinging to a surface. Cohesion is the attraction between molecules of the same substance, so the force acting between unlike substances is adhesion.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
Which form of heat is absorbed when a substance changes directly from a solid to a gas?
Show the answer and explanation
Answer: Latent heat.
Why: Latent heat is absorbed during a change of state without any change in temperature, including the direct solid-to-gas change called sublimation. The energy goes into breaking the bonds between molecules rather than raising the temperature.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
The heat required to change a liquid to a gas at constant temperature is the latent heat of
Show the answer and explanation
Answer: vaporization.
Why: The latent heat of vaporization is the energy required to change a liquid into a gas at a constant temperature. Condensation is the reverse process (gas to liquid) and fusion applies to melting, so vaporization is the correct term.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
A substance made of two or more different elements that are chemically bonded together is
Show the answer and explanation
Answer: a compound.
Why: A compound is formed when two or more different elements are chemically bonded together in fixed proportions, producing a substance with new properties. A mixture involves no chemical bonding, so compound is the correct description.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
The smallest particle of an element that still retains the properties of that element is
Show the answer and explanation
Answer: an atom.
Why: The atom is the smallest particle of an element that retains the element's identity and cannot be subdivided by ordinary chemical means. A molecule is a combination of atoms, and a compound is a substance of bonded elements, so the atom is the correct unit.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
A compound is best described as a substance in which two or more elements are
Show the answer and explanation
Answer: chemically bonded together to form a new material.
Why: A compound is formed when two or more elements are chemically bonded together in fixed proportions, producing a substance with new properties. Merely mixing elements physically gives a mixture, not a compound, because no chemical bond is created.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
In how many physical states can a substance such as water exist?
Show the answer and explanation
Answer: Three.
Why: Water can exist in three common states of matter: solid (ice), liquid (water), and gas (steam or water vapor). The state depends on temperature and pressure, and water changes between all three without altering its chemical composition.· FAA-H-8083-30 — Physics for Aviation
AM.I.JTap an answer
One newton of force is equal to
Show the answer and explanation
Answer: one kilogram-meter per second per second.
Why: By Newton's second law (force = mass x acceleration), one newton is the force that accelerates a one-kilogram mass at one meter per second squared, so 1 N = 1 kg·m/s². Force uses kilograms of mass and meters, not kilograms-force or grams and centimeters.· FAA-H-8083-30 — Physics for Aviation

That is a free sample of the 320 questions tagged to ACS AM.I.J. A free account adds three practice sessions a day and one timed exam-simulator attempt; the full bank, the adaptive engine that serves you more of whatever you keep missing, and unlimited exam simulations come with the Complete plan.

Failed AM.I.J on your AKTR?

Enter the ACS codes from your FAA fail report and get a targeted study plan — the exact areas the examiner must re-test you on, with the handbook references for each.

Build my remediation plan

Related subject areas

The areas that share the most ground with AM.I.J — study them alongside it.

Mathematics (AM.I.H)
Weight and Balance (AM.I.C)
Turbine Engines (AM.III.B)
Flight Controls (AM.II.C)

Frequently asked questions

What is the difference between absolute pressure and gauge pressure?: Gauge pressure is measured against the surrounding atmosphere, so an ordinary pressure gauge reads zero when it is open to the air even though real pressure is acting on it. Absolute pressure is measured from a perfect vacuum, so it equals the gauge reading plus atmospheric pressure, about 14.7 psi at sea level. Gas law calculations use absolute pressure.
What does specific gravity actually compare?: For a liquid or a solid, specific gravity compares the density of that substance to the density of pure water. Because it is a density divided by a density, the units cancel and the result is a pure number with no unit attached. A value above one means the substance is denser than water, and a value below one means it is less dense.
How do I tell conduction, convection, and radiation apart?: Conduction moves heat through direct contact within or between materials, as when a hot cylinder heats the fins bolted to it. Convection moves heat by the bulk motion of a fluid, so warmed air or oil physically carries energy from one place to another. Radiation needs no medium at all and travels as electromagnetic waves, which is how the sun heats a ramp.
What does Bernoulli's principle say for the written test?: For a fluid moving through a tube or duct, an increase in velocity is accompanied by a decrease in static pressure, and a decrease in velocity brings static pressure back up. That is why static pressure drops at the narrow throat of a venturi where the flow speeds up. On the test, the correct answer for rising velocity is falling static pressure.
Do I have to memorize formulas for this area?: Only a short list. Know that absolute pressure equals gauge plus atmospheric, that work equals force times distance and power is work divided by time, that mechanical advantage is resistance divided by effort, and the basic gas law relationships. Most questions test whether you know which quantity rises when another falls, not whether you can grind through a long calculation.

All 40 ACS areas

General

Airframe

Powerplant

Primary sources

Drill ACS AM.I.J inside the full General bank

Adaptive engine, timed exam simulator, ACS-code remediation, and oral prep — everything you need to pass.

Start free See plans