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Physics Key Concepts and Principles

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  • Newton's First Law of Motion

    An object remains at rest or in uniform motion unless acted upon by a net external force, illustrating the concept of inertia.

  • Newton's Second Law of Motion

    Acceleration is proportional to net force and inversely proportional to mass, expressed as \(F=ma\).

  • Newton's Third Law of Motion

    For every action, there is an equal and opposite reaction between two interacting objects.

  • Linear Momentum

    Momentum is the product of mass and velocity, \(p=mv\), and is a vector quantity.

  • Impulse

    Impulse is the change in momentum caused by a force applied over time: \(J=F\Delta t=\Delta p\).

  • Conservation of Momentum

    In a closed system with no external forces, total momentum remains constant: \(p_{initial} = p_{final}\).

  • Ohm's Law

    Voltage across a conductor is proportional to current and resistance: \(V=IR\).

  • Electrical Resistance Formula

    Resistance depends on resistivity, length, and cross-sectional area: \(R=\rho \frac{L}{A}\).

  • Electric Power

    Power is the rate of energy conversion: \(P=VI\), also \(P=I^2R\) or \(P=\frac{V^2}{R}\).

  • Electric Field Strength

    Electric field is force per unit charge: \(\vec{E} = \frac{\vec{F}}{q}\), measured in N/C or V/m.

  • Coulomb's Law

    Force between two point charges: \(F = k_e \frac{|q_1 q_2|}{r^2}\), attractive or repulsive depending on charge signs.

  • Pascal's Principle

    Pressure applied to a confined fluid is transmitted equally in all directions.

  • Archimedes' Principle

    An object immersed in fluid experiences an upward buoyant force equal to the weight of displaced fluid: \(F_b = \rho_{fluid} V_{displaced} g\).

  • Hooke's Law

    Within elastic limits, stress is proportional to strain: \(\text{Stress} = E \times \text{Strain}\), where E is Young's modulus.

  • Law of Reflection

    The angle of incidence equals the angle of reflection: \(\theta_i = \theta_r\).

  • Snell's Law

    Refraction of light between media: \(n_1 \sin \theta_1 = n_2 \sin \theta_2\).

  • Total Internal Reflection

    Occurs when light passes from denser to less dense medium at angle > critical angle: \(\sin \theta_c = \frac{n_2}{n_1}\).

  • Capacitance

    Ability to store charge per voltage: \(C=\frac{Q}{V}\), energy stored: \(U=\frac{1}{2} C V^2\).

  • Kinematic Equation for Velocity

    Velocity under constant acceleration: \(v = v_0 + at\).

  • Projectile Motion Range

    Horizontal range: \(R = \frac{v_0^2 \sin 2\theta}{g}\).

  • Lorentz Force

    Force on charge moving in magnetic field: \(\vec{F} = q (\vec{v} \times \vec{B})\).

  • Faraday's Law of Induction

    Induced EMF equals negative rate of change of magnetic flux: \(\mathcal{E} = -\frac{\Delta \Phi_B}{\Delta t}\).

  • Radioactive Decay Law

    Number of nuclei decreases exponentially: \(N(t) = N_0 e^{-\lambda t}\).

  • Half-Life

    Time for half the nuclei to decay: \(t_{1/2} = \frac{\ln 2}{\lambda}\).

  • Sound Intensity Level

    Measured in decibels: \(L = 10 \log_{10} \left( \frac{I}{I_0} \right)\), where I is intensity and I0 is threshold.

  • Doppler Effect Formula

    Observed frequency: \(f' = f \cdot \frac{v + v_o}{v - v_s}\), with source and observer velocities.

  • First Law of Thermodynamics

    Change in internal energy equals heat added minus work done: \(\Delta U = Q - W\).

  • Work-Energy Principle

    Net work done equals change in kinetic energy: \(W_{net} = \Delta KE = \frac{1}{2} m v_f^2 - \frac{1}{2} m v_i^2\).