AP Physics 1 – Unit 6: Energy & Momentum

This set of flashcards covers key concepts in AP Physics related to energy and momentum, including definitions and formulas.

Torque

Twisting force that causes rotation, calculated as τ = rFsinθ.

Rotational Equilibrium

Condition when an object is not rotating or rotates at constant speed; ∑τ = 0.

Center of Mass (COM)

Balance point of an object where all mass appears to act.

Moment of Inertia (I)

Resistance to rotational motion; depends on mass and distribution relative to axis.

Angular Velocity (ω)

Rate of rotation measured rad/s

Angular Acceleration

Rate of change of angular velocity.

Rotational Newton’s 2nd Law

Torque causes angular acceleration T=Ia

Rolling Without Slipping

Condition when an object rolls smoothly, maintaining v = ωr.

Rotational Kinetic Energy

Energy due to rotation, calculated as KE_rot = ½Iω².

Conservation of Angular Momentum

If no external torque acts, angular momentum remains constant: L = Iω.

Work (W)

Force applied over a distance; W = Fdcosθ.

Kinetic Energy (KE)

Energy of motion; KE = ½mv².

Gravitational Potential Energy (PE)

Stored energy based on height; PE = mgh.

Spring Potential Energy

Energy stored in a compressed or stretched spring; PE_spring = ½kx².

Work Energy Theorem

Work done equals the change in kinetic energy: W_net = ΔKE.

Conservation of Mechanical Energy

If only conservative forces act, total mechanical energy remains constant: KEi + PEi = KEf + PEf.

Power (P)

Rate at which work is done P=W/t.

Momentum (p)

Mass in motion p = mv.

Impulse (J)

Change in momentum calculated as J=F change in t

Conservation of Momentum

If no external forces act, momentum before and after an event remains constant.

Types of Collisions

Elastic collisions conserve kinetic energy; inelastic do not; perfectly inelastic means the objects stick together.