Full Mock 4 — Rotational Mechanics Emphasis
Full Mock 4 for AP Physics C: Mechanics emphasises rotational mechanics. Practice moment of inertia integrals, angular momentum conservation, and rolling motion FRQs.
Moment of Inertia, Angular Momentum, and Rolling Motion
Full Mock 4 places the greatest emphasis of the mock series on rotational mechanics — Units 5 and 6 of AP Physics C: Mechanics. If you are preparing for FRQs that require deriving moments of inertia, analysing rolling-without-slipping scenarios, or applying angular momentum conservation, Mock 4 provides the most targeted full-exam practice available on GradePerfect.
Emphasis Areas in Full Mock 4
Moment of Inertia Integrals
Mock 4 contains multiple problems requiring the derivation of moment of inertia from the integral definition I = ∫r² dm. Unlike mock exams that simply ask you to apply a known formula, Mock 4 FRQs require you to construct the integral from scratch for a given geometry — a rod with non-uniform linear density, a hollow cylinder, or a disc with a hole cut in it. The ability to express dm correctly and set appropriate limits of integration is directly assessed.
Angular Momentum Conservation Problems
Several MCQ and FRQ problems in Mock 4 involve angular momentum conservation: a system changes its geometry (contracting or expanding), an external object is added to a rotating system, or a collision imparts angular momentum. Each scenario requires identifying whether the net external torque is zero and, if so, setting up L_i = L_f with the correct expressions for I and ω before and after the change.
Rolling Motion FRQs
Rolling-without-slipping FRQs in Mock 4 require applying both translational and rotational Newton's second law simultaneously, using the rolling constraint v = Rω to eliminate one variable. Problems may involve a cylinder, sphere, or hoop rolling down an incline, and ask for the acceleration, the friction force required for rolling (without slipping), or the final speed at the bottom using energy methods. Both force-method and energy-method approaches are tested.
Skills Developed by Mock 4
- Deriving I for non-standard mass distributions using integral calculus.
- Applying the parallel-axis theorem after an integration-based derivation of I_cm.
- Setting up and solving angular momentum conservation equations for complex rotational systems.
- Combining τ = Iα and F = ma with the rolling constraint to find acceleration.
- Using energy conservation including rotational KE for rolling-down-incline problems.