BackPhysics Study Guide: Kinematics, Energy, Momentum, Rotational Motion, and Waves
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Chapter 3: Kinematics in Two Dimensions; Vectors
Vectors and Scalars
Understanding the distinction between vectors and scalars is fundamental in physics. Vectors have both magnitude and direction, while scalars possess only magnitude.
Examples of vectors: displacement, velocity, acceleration, force
Examples of scalars: mass, temperature, energy
Addition and Subtraction of Vectors
Vectors can be added graphically using the tip-to-tail method or analytically using components.
Graphical Addition: Place the tail of one vector at the tip of another; the resultant vector is drawn from the tail of the first to the tip of the last.
Subtraction: Subtracting a vector is equivalent to adding its negative.
Multiplication by a Scalar: Changes the magnitude but not the direction (unless the scalar is negative).
Adding Vectors by Components
Vectors can be broken into x and y components for easier calculation.
Resultant:
Projectile Motion
Projectile motion involves two-dimensional motion under constant acceleration due to gravity.
Horizontal motion:
Vertical motion:
Parabolic trajectory: The path is a parabola.
Relative Velocity
Relative velocity describes how the velocity of an object appears from different reference frames.
Chapter 6: Work and Energy
Work Done by a Force
Work is the product of force and displacement in the direction of the force.
Constant Force: Force does not change during displacement.
Varying Force:
Kinetic Energy and the Work-Energy Principle
Kinetic energy is the energy of motion. The work-energy principle states that the net work done on an object equals its change in kinetic energy.
Potential Energy
Potential energy is stored energy due to position or configuration.
Gravitational potential energy:
Elastic potential energy:
Conservative and Nonconservative Forces
Conservative forces: Work done is path-independent (e.g., gravity, spring force).
Nonconservative forces: Work done depends on the path (e.g., friction).
Mechanical Energy and Its Conservation
Mechanical energy:
Conservation: In absence of nonconservative forces,
Energy Conservation with Dissipative Forces
When nonconservative forces (like friction) are present, mechanical energy is not conserved, but total energy is.
Chapter 7: Linear Momentum
Momentum and Relation to Force
Momentum is the product of mass and velocity. Force is the rate of change of momentum.
Conservation of Momentum
In a closed system, total momentum before and after an event is constant.
Collisions and Impulse
Impulse:
Elastic collisions: Both momentum and kinetic energy are conserved.
Inelastic collisions: Only momentum is conserved.
Center of Mass
Chapter 8: Rotational Motion
Angular Quantities
Angular displacement:
Angular velocity:
Angular acceleration:
Rotational Dynamics: Torque and Rotational Inertia
Torque:
Rotational inertia:
Newton's second law for rotation:
Rolling Motion Without Slipping
Condition:
Chapter 11: Oscillation and Waves
Simple Harmonic Motion (SHM)
Equation:
Period:
Energy in SHM:
Damped and Forced Oscillations
Damped: Amplitude decreases over time due to energy loss.
Forced: External force drives the system, possibly causing resonance.
Waves: Types and Properties
Transverse waves: Oscillations perpendicular to direction of propagation.
Longitudinal waves: Oscillations parallel to direction of propagation.
Wave speed:
Reflection, Transmission, and Interference
Reflection: Wave bounces off a boundary.
Transmission: Wave passes through a boundary.
Interference: Principle of superposition:
Standing waves: Formed by interference of two waves traveling in opposite directions.
Additional info:
Sections referenced: Ch3, Ch6, Ch7 (7.1–7.6 and 7.7), Ch8 (8.1–8.6), Ch11 (11.1–11.22) are included in this guide.