AP Physics C: Mechanics flashcards
AP Physics C: Mechanics · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Instantaneous velocity
- The rate of change of position at a particular instant, equal to the derivative dx/dt and to the slope of the position-time graph at that point.
- Constant-acceleration displacement
- For constant acceleration, displacement is x − x0 = v0 t + ½ a t², where v0 is initial velocity and t is elapsed time.
- Projectile horizontal motion
- With negligible air resistance, a projectile's horizontal velocity stays constant because no horizontal force acts, so horizontal displacement equals v_x t.
- Centripetal acceleration
- For an object moving in a circle of radius r at constant speed v, acceleration points toward the center with magnitude a_c = v²/r.
- Relative velocity
- The velocity of object A measured in B's frame equals v_A − v_B, where both velocities are measured in a common inertial frame.
- Newton's second law
- The net force on a body equals the rate of change of its momentum, ΣF = dp/dt, which reduces to ΣF = ma when mass is constant.
- Static friction maximum
- Static friction adjusts up to a maximum value μ_s N, where N is the normal force; it equals whatever is needed to prevent slipping until that limit.
- Kinetic friction
- When surfaces slide, kinetic friction has magnitude f_k = μ_k N and points opposite the relative motion of the surfaces.
- Hooke's law force
- An ideal spring exerts a restoring force F = −kx, directed opposite the displacement x from equilibrium, with k the spring constant.
- Uniform circular motion net force
- The net inward force on an object in uniform circular motion has magnitude mv²/r; it is provided by real forces such as tension, gravity, or friction.
- Work by constant force
- Work equals F d cosθ, where F is force magnitude, d is displacement magnitude, and θ is the angle between force and displacement.
- Work-energy theorem
- The net work done on an object equals its change in kinetic energy: W_net = ½mv_f² − ½mv_i².
- Conservative force
- A force is conservative when the work it does between two points is path-independent, allowing a potential energy function U with F = −dU/dx.
- Mechanical energy conservation
- If only conservative forces do work, the sum K + U remains constant, so changes in kinetic energy equal opposite changes in potential energy.
- Impulse
- Impulse is the integral of force over time, J = ∫F dt, and equals the change in momentum of the object experiencing the force.
- Momentum conservation
- If the net external impulse on a system is zero, its total momentum remains constant even when internal forces act between parts.
- Perfectly inelastic collision
- In a perfectly inelastic collision the objects stick together and move with common velocity, conserving momentum but losing the maximum kinetic energy allowed by momentum conservation.
- Elastic collision
- A collision in which total kinetic energy is conserved as well as momentum; for two bodies the relative speed of approach equals the relative speed of separation.
- Center of mass velocity
- The center-of-mass velocity equals total momentum divided by total mass, v_cm = Σm_i v_i / Σm_i, and obeys F_ext = M a_cm.
- Torque
- Torque about a point is τ = r × F, with magnitude rF sinθ, where θ is the angle between the position vector and force.
- Rotational inertia
- Rotational inertia I = Σm_i r_i² measures resistance to angular acceleration and depends on mass distribution about the chosen axis.
- Parallel-axis theorem
- The rotational inertia about any axis equals I_cm + Md², where I_cm is about a parallel axis through the center of mass and d is separation.
- Rotational equilibrium
- A rigid body is in rotational equilibrium when the net torque about any axis is zero; if also ΣF = 0, it remains at rest or moves with constant velocity.
- Rotational kinetic energy
- A rigid body rotating about a fixed axis has kinetic energy ½Iω², where I is rotational inertia about that axis and ω is angular speed.
- Rolling kinetic energy
- An object rolling without slipping has total kinetic energy ½Mv_cm² + ½I_cmω², with v_cm = Rω relating linear and angular speeds.
- Angular momentum
- For a rigid body about a fixed axis, angular momentum is L = Iω; more generally L = r × p for a particle.
- Angular momentum conservation
- If the net external torque on a system is zero, total angular momentum stays constant, so reducing rotational inertia increases angular speed.
- Simple harmonic motion condition
- Motion is simple harmonic when acceleration is proportional and opposite to displacement from equilibrium, a = −ω²x, giving sinusoidal position versus time.
- Mass-spring period
- An ideal mass-spring oscillator has angular frequency ω = √(k/m) and period T = 2π√(m/k), independent of amplitude.
- Simple pendulum period
- For small angular amplitudes, a simple pendulum has period T = 2π√(L/g), independent of mass and dependent on length L and gravitational acceleration g.
- SHM energy
- A simple harmonic oscillator has total energy ½kA², with kinetic and potential energy trading while the sum stays constant in the absence of damping.
- Physical pendulum period
- A rigid body pivoted about an axis a distance d from its center of mass oscillates with period T = 2π√(I/(mgd)), where I is about the pivot.