Physics HL Summer

All defs in DP1

Random Error

Errors due to unpredictable variations in measurement; reduced by repeated trials and averaging

Systematic Error

Constant errors due to equipment or experimental design; causes a shift in results; cannot be reduced by averaging

Absolute Uncertainty

The margin of error in a measurement, expressed in the same units as the measurement

Fractional/Percentage Uncertainty

The ratio of the absolute uncertainty to the measured value, often expressed as a percentage

Vector

A physical quantity that has both magnitude and direction

Scalar

A physical quantity that has magnitude only

Displacement

Distance traveled in a specific direction; a vector quantity

Velocity

The rate of change of displacement

Acceleration

The rate of change of velocity

Terminal Velocity

The constant maximum velocity reached by an object when the drag force equals the driving force

Newton's First Law

An object continues in a state of rest or uniform motion unless acted upon by an external net force

Newton's Second Law

The net force is proportional to the rate of change of momentum (F = delta p / delta t)

Newton's Third Law

If body A exerts a force on body B, body B exerts an equal and opposite force on body A

Dynamic Friction

The friction between two surfaces when they are in relative motion

Static Friction

The friction that prevents two surfaces from starting to slide past each other

Work Done

The product of force and displacement in the direction of the force (W = Fs cos theta)

Law of Conservation of Energy

Energy cannot be created or destroyed, only transformed from one form to another

Efficiency

The ratio of useful work or power output to the total work or power input

Momentum

The product of an object's mass and its velocity (p = mv)

Impulse

The change in momentum; defined as the product of average force and time

Elastic Collision

A collision in which both momentum and kinetic energy are conserved

Inelastic Collision

A collision in which momentum is conserved, but kinetic energy is not

Centripetal Acceleration

Acceleration directed toward the center of a circular path (a = v^2 / r)

Centripetal Force

The net force required to keep an object moving in a circle, directed toward the center

Angular Velocity

The rate of change of angle per unit time

Torque

The turning effect of a force; force multiplied by perpendicular distance to pivot

Ideal Gas

A theoretical gas with particles of negligible volume, no intermolecular forces, and elastic collisions

Absolute Zero

The temperature at which all molecular motion ceases (0 K or -273.15 C)

Avogadro’s Constant

The number of atoms or molecules in one mole of a substance (6.02 x 10^23)

Internal Energy

The sum of the random distribution of kinetic and potential energies of the molecules in a system

Nucleon Number

The total number of protons and neutrons in a nucleus

Isotope

Atoms of the same element with the same number of protons but a different number of neutrons

Half-life

The time taken for half of the radioactive nuclei in a sample to decay

Binding Energy

The work required to separate the nucleons of a nucleus to infinity

Simple Harmonic Motion (SHM)

Acceleration is directly proportional to displacement from equilibrium and directed opposite to it

Amplitude

The maximum displacement from the equilibrium position

Phase Difference

The measure of how out of step two oscillations or waves are

Transverse Wave

A wave where the oscillations are perpendicular to the direction of energy transfer

Longitudinal Wave

A wave where the oscillations are parallel to the direction of energy transfer

Principle of Superposition

When two waves overlap, the resultant displacement is the vector sum of individual displacements

Parallax

The apparent shift in position of a star against a distant background due to Earth's orbit

Light Year

The distance light travels in a vacuum in one year

Parsec

The distance at which 1 AU subtends an angle of 1 arcsecond

Luminosity

The total power radiated by a star

Postulate 1 of Relativity

The laws of physics are the same in all inertial reference frames

Postulate 2 of Relativity

The speed of light in a vacuum is constant for all observers regardless of motion

Inertial Frame of Reference

A frame of reference that is not accelerating

Proper Time

The time interval measured by an observer for whom the events occur at the same position

Proper Length

The length of an object measured by an observer at rest relative to the object

Lorentz Factor

A factor used to calculate time dilation and length contraction (gamma = 1 / sqrt(1 - v^2/c^2)