AP®︎ Physics 1: Unit 8 Practice Test

Essential Knowledge: 8.1.A.1

Distinguishing properties of solids, liquids, and gases stem from the varying interactions between atoms and molecules.

Essential Knowledge: 8.1.A.2

A fluid is a substance that has no fixed shape.

Essential Knowledge: 8.1.A.3

Fluids can be characterized by their density. Density is defined as a ratio of mass to volume. Relevant equation: $\rho = \frac{m}{V}$

Essential Knowledge: 8.1.A.4

An ideal fluid is incompressible and has no viscosity.

Essential Knowledge: 8.2.A.1

Pressure is defined as the magnitude of the perpendicular force component exerted per unit area over a given surface area, as described by the equation $P = \frac{F_{\perp}}{A}$.

Essential Knowledge: 8.2.A.2

Pressure is a scalar quantity.

Essential Knowledge: 8.2.A.3

The volume and density of a given amount of an incompressible fluid is constant regardless of the pressure exerted on that fluid.

Essential Knowledge: 8.2.B.1

The pressure exerted by a fluid is the result of the entirety of the interactions between the fluid’s constituent particles and the surface with which those particles interact.

Essential Knowledge: 8.2.B.2

The absolute pressure of a fluid at a given point is equal to the sum of a reference pressure $P_0$, such as the atmospheric pressure $P_{atm}$, and the gauge pressure $P_{gauge}$. Relevant equation: $P = P_0 + \rho gh$

Essential Knowledge: 8.2.B.3

The gauge pressure of a vertical column of fluid is described by the equation $P_{gauge} = \rho gh$.

Essential Knowledge: 8.3.A.1

Newton's laws can be used to describe the motion of particles within a fluid.

Essential Knowledge: 8.3.A.2

The macroscopic behavior of a fluid is a result of the internal interactions between the fluid's constituent particles and external forces exerted on the fluid.

Essential Knowledge: 8.3.B.1

The buoyant force is a net upward force exerted on an object by a fluid.

Essential Knowledge: 8.3.B.2

The buoyant force exerted on an object by a fluid is a result of the collective forces exerted on the object by the particles making up the fluid.

Essential Knowledge: 8.3.B.3

The magnitude of the buoyant force exerted on an object by a fluid is equivalent to the weight of the fluid displaced by the object. Relevant equation: $F_b = \rho V g$

Essential Knowledge: 8.4.A.1

A difference in pressure between two locations causes a fluid to flow.

Essential Knowledge: 8.4.A.1.i

The rate at which matter enters a fluid-filled tube open at both ends must equal the rate at which matter exits the tube.

Essential Knowledge: 8.4.A.1.ii

The rate at which matter flows into a location is proportional to the cross-sectional area of the flow and the speed at which the fluid flows. Derived equation: $\frac{V}{t} = Av$

Essential Knowledge: 8.4.A.2

The continuity equation for fluid flow describes conservation of mass flow rate in incompressible fluids. Relevant equation: $A_1v_1 = A_2v_2$

Essential Knowledge: 8.4.B.1

A difference in gravitational potential energies between two locations in a fluid will result in a difference in kinetic energy and pressure between those two locations that is described by conservation laws.

Essential Knowledge: 8.4.B.2

Bernoulli’s equation describes the conservation of mechanical energy in fluid flow. Relevant equation: $P_1 + \rho gy_1 + \frac{1}{2}\rho v_1^2 = P_2 + \rho gy_2 + \frac{1}{2}\rho v_2^2$

Essential Knowledge: 8.4.B.3

Torricelli’s theorem relates the speed of a fluid exiting an opening to the difference in height between the opening and the top surface of the fluid and can be derived from conservation of energy principles. Derived equation: $v = \sqrt{2g\Delta y}$