AP Physics 1 FRQ Justification & Principles

A relevant physics principle, evidence from the situation, and reasoning connecting that principle to the conclusion.

Describing states what happens; explaining identifies the physics principle and shows why it happens.

State the prediction, identify the governing physics principle, and connect it logically to the situation.

Identify the net force and apply $\sum F=ma$ to explain the direction or magnitude of acceleration.

The claim must account for mass and net force; acceleration depends on $\frac{F_{\mathrm{net}}}{m}$.

Show all relevant external forces acting on the selected object, with correct directions and labels.

No. Velocity and acceleration describe motion; they are not forces.

Choose axes, assign signs, and write $\sum F_x=ma_x$ and $\sum F_y=ma_y$ as applicable.

Identify the system and determine whether external work or nonconservative energy transfers change its mechanical energy.

Define the system and establish that its net external impulse is zero or negligible over the interval.

Whether energy or momentum is conserved depends on the interactions crossing the system boundary.

The net impulse to the change in momentum through $\vec J=\Delta\vec p$.

Identify the variables on the axes, calculate $\frac{\Delta y}{\Delta x}$, and state the physical meaning with units.

Identify the plotted quantities and explain the physical quantity represented by the signed integral.

Both axes have correct physical quantities and units, with a suitable scale.

Identify the transformed variables and relate the slope or intercept to the physical model.

Specify what is changed, what is measured, what is controlled, and how the data answer the question.

Repeat measurements under comparable conditions to assess variability and improve precision.

Random uncertainty produces trial-to-trial scatter; systematic error produces a consistent bias.

Identify a specific source and explain how it affects the measurement or calculated result.

Compare the predicted relationship with the observed trend, accounting for measurement uncertainty.

State the relationship and support it using the relevant equation or physical principle.

Identify the governing relationship, hold appropriate variables constant, and show how the change affects the result.

Start with a valid principle, substitute applicable relationships, and show algebra leading to the requested expression.

Some scoring criteria award separate credit for setup, reasoning, units, or interpretation.

State its physical meaning and check that its sign, magnitude, and units are reasonable.

Show that the net force is zero and, when rotational equilibrium applies, that the net torque is zero.

Identify the pivot, force, lever arm, and sign convention using $\tau=rF\sin\theta$.

Identify the inward net force and connect it to $a_c=\frac{v^2}{r}$.

It names the net inward force requirement, not an additional physical interaction.

The restoring force or acceleration is proportional to displacement and directed toward equilibrium.

Define the system, identify external impulse, and determine which conservation laws apply.

That the selected system has no mechanical-energy change from nonconservative transfers or external work.

Use $W_{\mathrm{net}}=\Delta K$ and identify the forces contributing to net work.

Unsupported assertions, circular reasoning, and merely restating the question.

State disagreement clearly and support it with the governing physics principle.

To make the application of physical principles and the mathematical reasoning visible.

Include units for dimensional numerical results and graph quantities when applicable.

Use the earlier result consistently and show the reasoning required by the later part.

Confirm every requested prediction, calculation, explanation, graph, or justification has been addressed.