A fluid is a liquid or a gas : a substance with weak interactions between its particles.

What are the two properties of an ideal fluid ?

It is incompressible It has a viscosity of zero

Why do resistive forces not need to be considered for a flowing ideal fluid?

An ideal fluid has zero viscosity , so there is no resistance to its flow.

Density is the mass per unit volume of a substance.

How can the volume of an irregular object be found?

Use the displacement method : Lower the object into a displacement (eureka) can filled with water Collect the displaced water in a measuring cylinder The volume of displaced water equals the volume of the object

The density of an ideal fluid stays constant because the fluid is .......... .

The density of an ideal fluid stays constant because the fluid is incompressible .

True or False? Liquids and gases both have a fixed shape.

False. Fluids have no fixed shape : a liquid fills the base of a container and a gas expands to fill a container completely.

Pressure is the magnitude of the perpendicular force component exerted per unit area over a given surface area.

What causes the pressure on the surface of an object submerged in a fluid?

The interactions between that surface and the particles of the fluid.

Pressure is a .......... quantity, with magnitude only and no direction.

Pressure is a scalar quantity, with magnitude only and no direction.

True or False? A submerged object experiences pressure only on its top surface.

False. The fluid particles interact with every surface in contact with the fluid, so the object experiences pressure on all sides .

Define gauge pressure .

Gauge pressure is the pressure on a submerged object due to the weight of the column of fluid above it.

Define absolute pressure .

Absolute pressure is the total pressure from the fluid and its surroundings: reference pressure + gauge pressure .

Why does a pressure acting on a fluid's surface also act on a submerged object?

The fluid is incompressible , so any pressure it experiences at its surface is transferred to the object.

For a given fluid, gauge pressure depends only on the .......... of the fluid column, not on the container's shape.

For a given fluid, gauge pressure depends only on the height of the fluid column, not on the container's shape.

True or False? A steel cube and a cardboard box at the same depth in water experience different pressures.

False. Pressure depends on the fluid's density and the depth, not on the mass of the object, so both experience the same pressure.

AP®PhysicsCollege BoardPhysics 1: Algebra-BasedFlashcardsUnit 8: FluidsDensity & Pressure

Density & Pressure (College Board AP® Physics 1: Algebra-Based): Flashcards

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FrontFluid Properties
Define fluid.
FrontFluid Properties
What are the two properties of an ideal fluid?
BackFluid Properties
It is incompressible
It has a viscosity of zero

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Cards in this collection (20)

Define fluid.
A fluid is a liquid or a gas: a substance with weak interactions between its particles.
What are the two properties of an ideal fluid?
- It is incompressible
- It has a viscosity of zero
Why do resistive forces not need to be considered for a flowing ideal fluid?
An ideal fluid has zero viscosity, so there is no resistance to its flow.
Define density.
Density is the mass per unit volume of a substance.
State the equation for density.
$ρ = \frac{m}{V}$
- $ρ$ = density (kg/m³)
- $m$ = mass (kg)
- $V$ = volume (m³)
How can the volume of an irregular object be found?
Use the displacement method:
- Lower the object into a displacement (eureka) can filled with water
- Collect the displaced water in a measuring cylinder
- The volume of displaced water equals the volume of the object
The density of an ideal fluid stays constant because the fluid is ...........
The density of an ideal fluid stays constant because the fluid is incompressible.
True or False?
Liquids and gases both have a fixed shape.
False.
Fluids have no fixed shape: a liquid fills the base of a container and a gas expands to fill a container completely.
Define pressure.
Pressure is the magnitude of the perpendicular force component exerted per unit area over a given surface area.
State the equation for pressure.
$P = \frac{F_{⊥}}{A}$
- $P$ = pressure (Pa)
- $F_{⊥}$ = force component perpendicular to the surface (N)
- $A$ = area experiencing the force (m²)
What causes the pressure on the surface of an object submerged in a fluid?
The interactions between that surface and the particles of the fluid.
Pressure is a .......... quantity, with magnitude only and no direction.
Pressure is a scalar quantity, with magnitude only and no direction.
True or False?
A submerged object experiences pressure only on its top surface.
False.
The fluid particles interact with every surface in contact with the fluid, so the object experiences pressure on all sides.
Define gauge pressure.
Gauge pressure is the pressure on a submerged object due to the weight of the column of fluid above it.
State the equation for gauge pressure.
$P_{gauge} = ρ g h$
- $P_{gauge}$ = gauge pressure (Pa)
- $ρ$ = density (kg/m³)
- $g$ = acceleration due to gravity (m/s²)
- $h$ = height of the fluid column above the point (m)
Define absolute pressure.
Absolute pressure is the total pressure from the fluid and its surroundings: reference pressure + gauge pressure.
State the equation for absolute pressure.
$P_{total} = P_{0} + ρ g h$
- $P_{total}$ = absolute pressure (Pa)
- $P_{0}$ = reference pressure (Pa)
- $ρ$ = density (kg/m³)
- $g$ = acceleration due to gravity (m/s²)
- $h$ = height of the fluid column above the object (m)
Why does a pressure acting on a fluid's surface also act on a submerged object?
The fluid is incompressible, so any pressure it experiences at its surface is transferred to the object.
For a given fluid, gauge pressure depends only on the .......... of the fluid column, not on the container's shape.
For a given fluid, gauge pressure depends only on the height of the fluid column, not on the container's shape.
True or False?
A steel cube and a cardboard box at the same depth in water experience different pressures.
False.
Pressure depends on the fluid's density and the depth, not on the mass of the object, so both experience the same pressure.

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