IB Physics SL Paper 1+2 Definitions

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Displacement
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Measured distance and direction from an object's starting point.
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Speed
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The change in a moving object's displacement per unit time.
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Acceleration
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Change in velocity per unit time
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Terminal velocity
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The constant velocity reached when the force of gravity is equal to the force of drag.
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Mass
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A measure of a body's inertia.
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Inertia
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A body's reluctance to changes in its motion.
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Gravitational force
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Accounts for planetary motion; weakest of four fundamental forces.
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Weak interaction
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Responsible for radioactive decay; accounts for how the nucleus comes apart.
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Electromagnetic interaction
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Force between particles' charges (coulombic attraction/repulsion).
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Strong nuclear interaction
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Hold protons and neutrons together in the nucleus.
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Newton's first law
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Every object continues in a state of rest of uniform motion in a straight line unless acted upon by an external force.
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Equilibrium
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Static: object is at rest; not moving. Dynamic: object is moving with constant velocity.
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Newton's second law
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The rate of change of linear momentum of a particle is directly proportional to the impressed force acting upon it and takes place in the direction of the impressed force.
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Linear Momentum
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The product of an object's mass and its velocity.
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Impulse
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The change in momentum per unit time.
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Law of conservation of momentum
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If the total external force acting on a system is a zero then the momentum of the system remains constant (is conserved) or The momentum of a closed system is constant (conserved).
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Newton's third law
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When a force acts on a body, an equal and opposite force acts on another body somewhere in the universe.
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Work
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The amount of energy transferred to complete a task. or The product of the magnitude of a force and an object's displacement in the direction of that force.
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Work done on a system
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Positive
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Work done against a system
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Negative
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Kinetic Energy
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The energy of a moving object.
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Potential Energy
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Potential to do work based on an object's position.
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Thermal Energy
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The sum of the total potential energy and the random kinetic energy of the molecules of the substance making up the system.
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Chemical Energy
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Energy associated w/ electronic structure of atoms.
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Nuclear Energy
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Energy associated with the nuclear structure of atoms.
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Electrical Energy
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Energy associated with an electric current.
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Elastic Collision
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Mechanical energy is not lost.
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Inelastic Collison
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Mechanical energy is lost.
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Power
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Rate of working; work done per unit time.
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Efficiency
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The ratio of work going into a system to useful work coming out of a system.
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Centripetal force
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A force that causes circular motion.
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Examples of forces that provide a centripetal force
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Gravity; friction between road surface and a car's tires; magnets.
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Temperature
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Scalar quantity that gives an indication of the degree of hotness or coldness of a body; the average KE per molecule of a substance.
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Celsius scale
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0˚ = water's freezing point. 100˚ = water's boiling point.
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Kelvin scale
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0 = absolute zero (-273.16˚ C). Kelvin is Celsius + 273.16.
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Thermal energy can be transferred by:
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Conduction (a temperature difference causes the transfer of thermal energy from hotter to cooler areas). Convection (a temperature change causing the movement of fluid particles from a hot area to a cold area). Radiation (energy travelling through electromagnetic waves).
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Mole
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The amount of substance that contains as many elementary particles as there are in 0.012 kg of carbon-12. Always state the element when measuring in moles.
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Heat capacity
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The quantity of thermal energy needed to raise the temperature of a substance by one Kelvin.
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Specific heat capacity
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The quantity of thermal energy required to raise the temperature of a unit of mass of a substance by one Kelvin.
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Newton's law of cooling
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The rate of loss of heat of a body is proportional to the difference in temperature of the body and its surroundings.
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Moving particle/ Kinetic theory
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-All matter is composed of extremely small particles -All particles are in constant motion -If particles collide with neighboring particles, they conserve their kinetic energy -A mutual attractive force exists between particles
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Matter
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Anything that has mass and occupies space.
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Properties of solids
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-Closely packed particles -Strong bonds between neighboring particles -Potential energy due to force of attraction between particles
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Properties of liquids
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-Closely packed, strong bonds -Not rigidly held in position; bonds break and reform -Particles slowly and randomly move relative to each other -Variable shape -Slow diffusion -Kinetic Energy: vibrational, rotational, translational -Higher potential energy because spaces between particles are larger
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Properties of gases
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-Widely spaced particles that only interact significantly when they collide or come very close together -Random zig-zag motion of particles causes gases to be dispersed throughout any container they are placed in. -Diffusion is quick -High translational KE due to higher mean speeds -Greatest PE due to greater distance between particles
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Explaining phase changes with the moving particle theory
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As temp increases, vibrational KE increases; as KE increases, particles overcome forces binding them into a solid and begin spreading apart and slipping over one another, making a liquid. The same happens for gasses.
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Evaporation
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A change from the liquid state to the gaseous state that occurs at a temperature below the boiling point. High KE particles escape binding forces but not all particles are at high KE.
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Evaporative cooling
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As high-KE particles escape, total KE goes down causing a decrease in temp
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Latent heat
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The thermal energy which a particle absorbs in melting, evaporation or sublimation and gives out in freezing, condensing or sublimating. -Doesn't produce change in temp
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Latent heat of transformation
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The quantity of heat required to change one kilogram of a substance from one phase to another.
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Pressure
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Force exerted over an area.
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Ideal gas laws
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-Boyle: pressure of a gas at a constant temp is proportional to the gas' density -Charles Law: the volume of a fixed mass of gas at constant pressure is directly proportional to its absolute temperature.
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Displacement (in SHM)
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The distance that an oscillating system is from its equilibrium position at any particular instant during the oscillation.
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Amplitude
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The maximum displacement of an oscillating system from its equilibrium position.
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Period
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The time it takes an oscillating system to make one complete oscillation.
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Frequency
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The number of complete oscillations made by the oscillating system in one second.
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Phase difference
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The relation between the displacements of two oscillating systems. In phase: always at the exact same displacement as each other (0˚) Anti-phase: always at opposite displacement (180˚)
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Conditions of a simple harmonic oscillator
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Perfectly isochronous, whose amplitudes do not change with time.
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Conditions required for SHM
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Acceleration of a system is directly proportional to its displacement from its equilibrium position and directed toward the equilibrium position.
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Angular speed
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Number of radians through which a particle moves in one second.
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Angular frequency (wumbo)
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ω=2πf or ω=2πf/T
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Damped oscillations
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Oscillations for which the amplitude decreases with time.
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Natural frequency
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The frequency that a system will naturally hold when you set it in motion.
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Forced oscillation
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When you have to set a system in motion.
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Resonance
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The maximum amplitude attained when an oscillatory system is driven at a frequency equal to its natural frequency.
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Definition of a wave
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A means by which energy is transferred between two points in a medium without any net transfer of the medium itself.
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Medium
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Substance/object the wave is traveling through
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Transverse waves
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The source that produces the wave vibrates at right angles to the direction of travel of the wave. -Examples: seismic waves, em waves
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Longitudinal waves
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The source that produces the wave vibrates in the same direction as the direction of travel. -Ex: sound waves
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Crest
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The maximum height of the wave, i.e. the point at which the particles in the medium in which the waves travel have maximum displacement.
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Trough
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The minimum height of the wave, i.e. the point at which the particles in the medium in which the waves travel have minimum displacement.
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Compression
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The region of the wave where particles of the medium are \"bunched up.\"
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Rarefaction
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The region of the wave where the particles of the medium are \"stretched out.\"
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Intensity of a wave
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The energy that a wave transports per unit time across unit area of the medium through which it is traveling.
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Wavelength
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The distance along the medium between two successive particles that have the same displacement.
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Wave speed
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The speed at which energy is carried in the medium by the wave. -Depends only on the properties of the medium
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Reflection
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When a wave reaches a barrier, it is reflected in the opposite direction. -The amplitude of a reflected wave is slightly less than that of the original wave because some energy goes into the barrier. -Law of reflection: Reflected waves are reflected at the same angle as the initial wave in the opposite direction.
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Refraction
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The change in direction of travel of a wave resulting from a change in speed of the wave. -Determined by ratio of initial velocity to final velocity, and initial wavelength to final wavelength
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Snell's Law
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When a wave is passing from one medium to another, the ratio of the sines of the angles Ø1 and Ø2 between the normal drawn at a right angle to the medium is constant. -This ratio is the refractive index of the second medium.
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Diffraction
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When waves pass through a slit or any aperture, or pass the edge of a barrier, they spread out into the region that is not directly in the path of the waves.
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Constructive interference
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Waves \"stack;\" two positive waves superpose to make a larger wave.
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Destructive interference
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Waves cancel out; a positive wave and a negative wave superpose to decrease each other's effect .
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Nodes
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The points at which destructive interference will cause a wave not to be displaced.
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Antinodes
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The points of maximum constructive interference.
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Coherent sources
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Sources that have the same frequency and are in phase.
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Electric potential difference
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The power dissipated in a load per unit current in moving from one point to another. or The amount of electrical energy that is changed to other forms of energy when an amount of charge moves from one point to another. or The work done per unit charge in moving a positive charge from a point at higher potential to a point at lower potential.
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Electron Volt
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The energy acquired by an electron as a result of moving through a potential difference of one volt.
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Electric Current
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The rate at which charge flows past a given cross-section.
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Resistance
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The ratio of the potential difference across the material to the current that flows through it.
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Factors affecting resistivity
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length cross-sectional area resistivity temp
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Ohm's law
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Provided the physical conditions such as temperature are kept constant, the resistance is constant, and therefore the potential difference is directly proportional to the current flowing. (only applicable to ohmic conductors) V = IR
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Ohmic vs. Non-Ohmic resistors
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Ohmic resistors show a linear relationship between current and voltage, non-ohmic resistors do not.
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Electric Power
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The rate at which energy is supplied to or used by a device. It is measured in Joules per second (Watts) P = IV
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Electromotive force
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The work per unit charge made available by an electrical source.
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Internal resistance
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Resistance within a circuit or power source.
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Terminal voltage
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The measured voltage at the terminals of a power source.
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Series circuit
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-All components have only one current pathway -All components have the same current through them -The sum of the potential drop across each component is equal to the emf of the power source -The total/effective resistance of a series circuit is the sum of the separate resistances
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Parallel circuit
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-More than one current pathway -All components have the same potential difference across them -The sum of the currents flowing into any point is equal to the sum of the currents flowing out at that point
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Voltmeter
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-Always connected across a device (in parallel) -Has very high resistance, takes very little current -Ideally would have infinite resistance with no energy dissipated in it
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Ammeter
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-Always connected in series with a circuit -Has a very low resistance compared to the resistance of the circuit so that it will not significantly alter the current flowing in the circuit. -Would ideally have no resistance with no potential difference and no energy dissipated in it.
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Potentiometer
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A variable resistor that determines the potential difference across an output transducer.
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Newton's universal law of gravitation
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Every material particle in the Universe attracts every other material particle with a force that is directly proportional to the product of the masses of the particles and that is inversely proportional to the square of the distance between them.
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Gravitational field strength
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The force exerted per unit mass on a particle of small mass placed at that point in the field.
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Coulomb's law
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The force between two point charges varies with a force that is directly proportional to the product of the charges of the particles and that is inversely proportional to the square of the distance between them.
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Law of conservation of charge
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In a closed system, the amount of charge is constant.
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Conductors
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Have low electric resistance (contain electrons and positive and negative ions that are free to move).
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Insulators
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Have high electric resistance (electrons are held tightly by the atomic nuclei and are not free to move through material).
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Electric field strength
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The force per unit charge exerted on a positive test charge.
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Magnetic field strength
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(Someone help me out here, I couldn't find a good definition in my notes)
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Absorption spectra
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To change energy levels, electrons must absorb photons. This creates a spectrum of lines specific to elements.
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Isotopes
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Forms of elements that are chemically identical but have different masses.
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Neutron
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Uncharged particles in the nucleus that explain the existence of isotopes
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Natural radioactive decay
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When elements emit radiation spontaneously (without external excitation).
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Alpha radiation
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Emission of an alpha particle; range of 4 cm, easily stopped by a few sheets of paper (least penetrating, most harmful).
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Alpha particle
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A helium-4 nucleus
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Beta radiation
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Travels several meters; can penetrate aluminium sheets (medium level of penetration, medium harmfulness).
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Gamma Radiation
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Short-wavelength em waves. Parent nuclide decays to an excited state of the daughter nuclide; daughter nuclide then drops to its ground state by emitting a photon. (Most penetrating, least harmful).
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Half-life
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The time it takes the activity of a sample of the element to halve in value or the time it takes for half the atoms in the sample of element to decay.
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Becquerel
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The number of atoms decaying per unit time.
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Atomic mass unit (U)
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1/12 the mass of an atom of carbon-12; 1 U = 1.661*10^-27 kg
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Einstein's mass-energy relation
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The mass of an object that is moving relative to an observer will be measured as greater than the object's mass at rest (m0).
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Mass defect
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Represents the energy released in a reaction. If positive, reaction will take place spontaneously, if negative, reaction will require added energy.
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Binding energy
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The energy required to separate the nucleus into it individual nucleons. or The energy that would be released in assembling a nucleus from its individual nucleons.
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Fusion
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Arranging two nuclei to fuse together. Very high temps and pressures are required to overcome coulombic repulsion.
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Fission
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A nucleus is split into two by emitting radioactive particles.
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Energy degradation
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Energy that has been transformed into a less useful form.
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Sankey diagram
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Thickness of arrows represent amount of energy used in each transformation
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Non-renewable energy
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Source that is depleted when used, such as coal, oil, natural gas, etc.
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Renewable energy
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A source that is permanent or that can be replenished as it is used.
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Energy density
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The amount of potential energy stored in a fuel per unit mass or per unit volume.
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Advantages/disadvantages of nuclear energy
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Advantages: -High energy density -More renewable than fossil fuels Disadvantages: -Hazards -Possible wartime applications -Radioactive waste
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Advantages/disadvantages of hydropower
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Advantages: -No emissions -Renewable Disadvantages: -Large dams needed; causes population displacement -Possibility of dam failure
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Advantages/disadvantages of geothermal power
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Advantages: -efficient, minimally destructive Disadvantages: -only useful in volcanic areas
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Advantages/disadvantages of tidal power
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Advantages: -No emissions -Renewable Disadvantages: -Few areas have required tidal range -High construction costs
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Advantage/disadvantages of solar power
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Advantages: -Renewable -Can be used nearly everywhere Disadvantages: -Expensive -Intermittent (no output at night or on cloudy days) -Small energy output per unit area
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Advantages/disadvantages of wind energy
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Advantages: -Cheap -Clean -Renewable Disadvantages: -Expensive -Noisy
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Fuel enrichment
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Thermal reactor fuel is a mixture of fissionable and fertile material enriched with U-235 and U-238 isotopes.
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Moderator (in a nuclear reactor)
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Material that will slow down the fast neutrons to the speed of the slow thermal neutrons. (Placed around reactor core).
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Control rods (in a nuclear reactor)
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Made of material that will absorb neutrons
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Coolant (in a nuclear reactor)
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Removes thermal energy, converting water to steam. In this process, the water becomes radioactive.
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Heat exchanger (in a nuclear reactor)
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System acting as a heat engine driven by chemical reactions or by nuclear reactions.
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Active solar heating
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Using solar heaters to convert solar energy into heat energy (often used for domestic hot water).
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Photovoltaic solar cells
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Photons from radiant energy excite electrons in a doped semi-conducting material, allowing electrons to flow in an external circuit to produce electrical energy.
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Thermoelectric converters
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Bars of doped silicon are used to create an emf between hot and cold ends.
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Ways of producing hydroelectric power
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Water storage in lakes, tidal water storage, pump storage.
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Intensity of the Sun's radiation
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The amount of solar energy per second that falls on an area of 1 m2 of the upper atmosphere perpendicular to the Sun's rays.
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Albedo
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The ratio between the incoming radiation and the amount reflected expressed as a coefficient or percentage.
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Enhanced greenhouse effect
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Global warming caused by human production of excess greenhouse gasses
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Black-body radiation
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Radiation emitted by a perfect emitter
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Emissivity
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The ratio of the amount of energy radiated from a material at a certain temp and the energy that would come from a black body at the same temp.
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Surface heat capacity
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The energy required to raise the temp of a unit area of a planet's surface by one degree kelvin.
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