Vocab List

Unit 1: Introduction Accuracy – how well the results of a measurement agree with the “accepted” value Dependent Variable – the factor in an experiment that depends on the independent variable Derived Unit – a combination of fundamental units used to simplify notation Dimensional Analysis – a method of treating units as algebraic quantities Direct Relationship – a linear relationship that passes through the origin Hypothesis – a testable, educated guess Independent Variable – the factor that is manipulated during an experiment Inverse Relationship – the product of the two variables is a constant Line (curve) of Best Fit - a line (curve) that best passes through or near graphed data Linear Relationship – a relationship between two variables whose graphed data points lie on a straight line Measurement – a comparison between an unknown quantity and a standard Physics – the study of matter and energy Precision – the degree of exactness of a measurement Quadratic Relationship – a parabolic relationship, one variable depends on the square of another Scientific Fact – a repeatable observation accepted by experts in the field Scientific Law – a well established rule that describes, but does not explain a pattern in nature Scientific Method – a systematic method of observing, experimenting and analyzing to answer questions about the natural world Scientific Notation – a standard method of writing numbers ( a x 10b) Scientific Theory – a model based on numerous observations, supported by experimental results that may explain how things work Significant Digits – the valid digits in measurement the number of which indicates the precision of a measurement Unit – a standard quantity with which other similar quantities can be compared

Unit 2: Modeling Motion Acceleration - the time rate of change of the velocity

Acceleration due to Gravity – the acceleration of an object in free fall (g) Average Velocity – displacement / time Displacement – the change in the position of an object Distance – the total length of a path that an object travels Free Fall – an object moving under the influence of gravity only Instantaneous Velocity – the velocity of an object at a particular instant in time Kinetic Energy – the energy of an object due to its motion Linear Motion – an object’s motion along a straight line (1-dimension) Meter – fundamental SI unit of length Origin – a reference point Position – the straight line distance and direction from the origin Scalar – a quantity with magnitude (size) only Second – fundamental SI unit of time Speed – the distance and object moves in a unit time Uniform motion – motion with constant velocity (a=0) Vector – a quantity with magnitude (size) and direction Velocity – the time rate of change of the position

Unit 3: Newton’s Laws Action / Reaction – interaction force pair, same magnitude opposite direction Contact Force – an interaction (force) between two objects that requires touching  Dynamic Equilibrium - forces are balanced, particle is moving, ∑ F = 0 , a = 0 , v ≠ 0  Equilibrium – forces are balanced, ∑ F = 0 , a = 0 Field Force – an interaction (force) between two objects that does not require contact Force – an interaction between two objects, a push or a pull Free Body Diagram –a physical model that represents the forces acting on a system Friction – contact force that acts to oppose sliding motion between surfaces

Gravitational force – the attractive force between two objects that is directly proportional to the mass of the objects Inertia – the resistance of an object to a change in its motion Inertial Mass – a measure of an object’s inertia Net force – the vector sum of the forces (resultant) Newton – the force that imparts a 1 m/s2 acceleration on a 1-kilogram mass, a derived SI unit for force Newton’s 1st Law – an objects motion will be unchanged (equilibrium) if and only if the net force on the object is zero Newton’s 2nd Law – the acceleration of an object is directly proportional to the net force and   inversely proportion to its mass. ∑ F = ma Newton’s 3rd Law – forces come in pairs (action/reaction) Normal – contact force between surfaces, perpendicular to the contact surface Resolution of Forces – the process of determining the components of a force Resultant – the vector sum Spring Force – a restoring force, opposite the displacement of the end of the spring  Static Equilibrium – forces are balanced, particle is at rest ∑ F = 0 , a = 0 , v = 0 Tension – the pull exerted by a string, rope or cable Thrust- a general term for the forces that move objects such as rockets, planes, cars etc Unbalanced Force – a nonzero net force Vector Component – the ‘part’ of a vector in a given direction Weight – a field force due to gravitational attraction between two objects, generally Earth and an object

Unit 4: Applications of Newton’s Laws Coefficient of Friction – the ratio of the maximal frictional force and the normal force Equilibrant - a force that places an object in equilibrium Gravitational Field Strength – the force per unit mass at a given point in a gravitational field Gravitational Potential Energy – the energy change of an object resulting from lifting the object to a height above Earth’s surface

Hooke’s Law – the force acting on a spring is directly proportional to the amount that the spring is stretched or compressed Kinetic Friction - friction that acts on moving objects Projectile - an object shot through the air that after receiving an initial thrust, travels through the air only under the influence of gravity. [2-d free fall] Range -the horizontal distance traveled by a projectile Spring Constant – the constant of proportionality between the applied force and the stretch or compression of a spring, depends on the stiffness of the spring Static Friction – the frictional interaction between two surfaces when there is no motion between the two surfaces Trajectory – the path of a projectile through space

Unit 5: Impulse and Momentum Closed system – a system that does not gain or lose mass Impulse – the area under the force vs. time graph, the product of the average net force on an object and the time interval over which the force acts Impulse-momentum theorem – the impulse on an object is equal to the change in the objects momentum. This is a cause and effect relationship. Law of Conservation of Momentum – the momentum of any closed, isolated system does not change. Momentum – the product of an object’s mass and velocity

Unit 6: Work and Energy Conservative Force - a force for which work done by it is independent of the path taken Elastic Collision – a collision in which the kinetic energy is conserved Elastic Potential Energy – the potential energy stored in an object due to a change in its shape Electromagnetic energy –the energy associated with electric or magnetic fields Energy – the ability to do work Generator – device that converts mechanical energy into electrical energy Ideal Mechanical System – a closed system in which no friction or other non-conservative force is acting Inelastic Collision – a collision for which the kinetic energy after the collision is less than the kinetic energy before the collision

Internal Energy – total potential and kinetic energy of the particles that make up and object, but excluding the energy of the system as a whole Joule – a derived SI unit equal to the work done when a force of one Newton produces a displacement of 1 meter. Law of Conservation of Energy – in a closed, isolated system, the total energy in constant Non-conservative Force – a force for which the work done by it depends on the path taken Mechanical Energy – the sum of the kinetic and potential energies of a system Motor – device that converts electric energy into mechanical energy as a result of forces on a current-carrying conductor in a magnetic field Non-ideal Mechanical System - a system in which a non-conservative force such as friction is acting Nuclear Energy – the energy released in a nuclear reaction (eg: Fission or Fusion) Photocell – device that converts light, a form of electromagnetic radiation, to electrical energy Potential Energy – the energy due to the position or condition of an object, Power- the rate at which work is done Simple pendulum – a mass (bob) attached to one end of a string or wire that is attached at the other end to a pivot point Thermal Energy – a measure of the internal motion of an object’s particles, the total kinetic energy of an object’s particles Total Energy – the total energy of a non-ideal system is the sum of the PE, KE and Internal Energy Watt – a derived SI unit for power equal to 1 Joule per second Work – the transfer of energy by mechanical means; is done when a force is exerted on an object in the direction of motion; area under the Force vs. position graph Work-Energy Theorem – when work is done on an object, a change in kinetic energy occurs

Unit 7: Fundamental Interactions Centripetal Acceleration – the acceleration toward the center of a curvature of a curved path Centripetal Force – the net force causing a centripetal acceleration Coulomb – the SI standard unit of charge Coulomb’s Law – the force between two charges varies directly with the product of the charges and inversely with the square of the distance between them

Electric Charge – the property of particles that governs the electromagnetic interaction Electron – a fundamental particle (lepton) that has a charge of -1e or -1.6 x 10-19 Coulombs Elementary Charge – the smallest quantity of charge observed in nature e = 1.6 x 10-19 Coulombs Gravitational Mass – the property of particles that governs the gravitational force Law of Universal Gravitation – the force between two masses varies directly with the product of the masses and inversely with the square of the distance between them Neutron – a fundamental particle (baryon) that has a charge of 0e Nucleon – particles found in the nucleus of an atom (protons & neutrons) Period – the time required for a repetitive motion to repeat one complete cycle of motion Proton – a fundamental particle (baryon) that has a charge of +1e or 1.6 x 10-19 Coulombs Strong Nuclear Force – very Strong, short ranged attractive force between nucleons Uniform Circular Motion – the motion of an object traveling in a circular path with constant speed Weak Nuclear Force – short ranged, nuclear force responsible for particle decay

Unit 8: Electrical Properties of Matter Capacitance – the ratio of an object’s stored charge to its electric potential difference Capacitor – an electric device used to store charge Charging by conduction – the process of charging a neutral object by touching it with charged objects Charging by induction – the process of charging an object without touching it Conductor – a material through which a charge will move freely Electric field – the field that exists around a charged object Electric field line – lines that provide a picture of an electric field Electric potential difference – the change in electric potential energy per unit charge in an electric field Electric potential energy – potential energy due to the position of a charge in an electric field Electronvolt – an small unit of energy; the amount of work necessary to move one electron across a potential difference of 1 Volt

Electroscope – a device that is used to detect electric charges Electrostatics – the study of charges at rest Equipotential – the electric potential difference of zero between two or more positions in an electric field Grounding – the process of removing excess charge by touching an object to the Earth Insulator – a material through which a charge will not move easily Law of Conservation of Charge – a material through which a charge will not move easily Neutral – an object that has a net charge of zero Volt – a derived SI unit for electric potential difference equal to one Joule per Coulomb

Unit 9: Electric Circuits Ammeter – a device for measuring electric current Ampere – the fundamental SI unit of electric current; equal to one coulomb per second Battery – a combination of two or more electrochemical cells; a direct current voltage source Cell – a device that converts chemical energy to electrical energy Conductivity – a property of a material that describes the availability of charges that are free to move under the influence of an electric field Conventional Current – a flow of positive charges that move from higher potential to lower potential Electric Circuit – a closed loop or pathway that allows electric charges to flow Electric Current – the rate at which charges pass a given point Equivalent Resistance – the single resistance that could replace several resistors in a circuit Kilowatt-hour – an energy unit used by electric companies to measure energy sales; 1 kWh 3.6x106 Joules Ohm – the derived SI unit of electrical resistance; equivalent to 1 volt per ampere Ohm’s Law – at a constant temperature the resistance of a conductor is constant Ohm-meter – the SI unit for resistivity Parallel Connection – each circuit element is connected in a separate branch

Resistance – the ratio of the applied voltage across a conductor to the corresponding current through the conductor Resistivity – a property of a material that describes how strongly a material resists the flow of electrons Resistor – an electrical device designed to have a definite amount of resistance Series Connection – all circuit elements are connected end to end to proved a single path for current Superconductor – a material with zero resistance that can conduct electricity without a loss of energy Switch – a device for making, breaking or changing the connections in an electric circuit Voltmeter – a device for measuring potential difference

Unit 10: Magnetism Domain – a very small region that is formed when magnetic fields of the electrons in neighboring atoms are aligned in the same direction Electromagnetic Induction – the process of generating a potential difference across a conductor due to the relative motion of the conductor and a magnetic field Magnet – a material in which the spinning electrons of its atoms are aligned in the same direction Magnetic Field – the area around a magnet or moving charge where a magnetic force exists Magnetic Field (flux) Lines – imaginary lines that map out a magnetic field Magnetic Field Strength (flux) – the number of magnetic flux lines per unit area passing through a surface Magnetic Force – a force between two charges moving relative to each other Magnetic Pole – a location where the magnetic field has the highest intensity

Unit 11: Wave Model Amplitude –in any periodic motion, the maximum displacement of an object from equilibrium Angle of Incidence – the angle between the incident ray and the normal to the surface at the point where the ray meets a boundary

Angle of Reflection – the angle between the reflected ray and the normal to the surface at the point where the ray meets a boundary Angle of Refraction – the angle between the refracted ray and the normal to the surface at the point where the ray meets a boundary Antinode – the point of maximum displacement of a medium when two wave pulses meet Constructive Interference – the effect produced when two in-phase waves pass simultaneously through a medium causing an increase in amplitude Crest – the high point in a wave Decibel –The unit of measurement for sound level Destructive Interference - the effect produced when two out of-phase waves pass simultaneously through a medium causing a decrease in amplitude Diffraction – the spreading of wave fronts into a region behind a barrier Diffuse Reflection – the scattering of light off of a rough surface Doppler Effect – a change in the observed frequency and wavelength due to the relative motion of a wave source and the observer Electromagnetic Spectrum – the complete range of frequencies and wavelengths if electromagnetic waves Electromagnetic Wave – periodically changing electric and magnetic fields that travels through a vacuum Frequency – the number of cycles of a periodic motion that occur per second Hertz – derived SI unit of frequency; 1 Hertz = 1 cycle per second Image – the combination of image points in an optical device from which the object seems to originate Incident Wave (ray) – a ray that originates in a medium and is incident on a boundary with another medium Index of Refraction – the ratio of the speed of light in a vacuum to the speed of light in a particular medium Interference – results from the superposition of two or more waves Law of Reflection – the angle of incidence is equal to the angle of reflection Longitudinal Wave – a mechanical wave in which the disturbance is in the same direction, parallel to, the direction of propagation

Mechanical Wave – A wave that can not travel through a vacuum Medium – material through which waves travel Monochromatic Light – light of a single frequency (color) Node – a stationary point where two wave pulses meet, having a displacement of zero Normal – a reference line drawn perpendicular to a surface Object – a source of light rays that enter an optical device Period – the time required for an object to complete one cycle of a periodic motion Periodic Motion – any motion that repeats itself in a regular cycle Periodic Wave – a series of regularly repeated disturbances in a field or medium Phase – the position of a point on a wave relative to another point on the same wave Pitch – the highness or lowness of a sound wave; depends on the frequency Plane Mirror – a flat smooth surface form which a wave is reflected Principle of Superposition – the displacement of a medium caused by two or more waves is the vector sum of the displacements of the individual waves Ray Model of Light – a model that represents light as a ray that travels in a straight path Reflected Wave (ray) – a wave that rebounded from a boundary Refracted Wave (ray) – a ray that results from an incident ray crossing a boundary obliquely Refraction – the change in direction of a wave as it crosses a boundary obliquely Resonance –the vibration of an object at its natural frequency due to the action of a vibrating source of the same frequency Simple Harmonic Motion – a motion that occurs when the restoring force on an object is directly proportional to the object’s displacement from equilibrium Snell’s Law – the product of the index of refraction of a medium and the sine of the angle that the ray makes with the normal is a constant across a boundary Sound Level – a logarithmic scale used to measure the amplitude of a sound wave Sound Wave – a longitudinal pressure variation transmitted through matter Specular (regular) Reflection – a reflection produced by a smooth surface

Standing Wave – a wave that appears to be standing still; produced by two identical waves traveling in opposite directions Surface Wave – a mechanical wave in which the particles move both parallel and perpendicular to the direction of propagation Transverse wave – a wave that vibrates perpendicular to the direction of propagation Trough – the low point of a wave Vacuum – a region of empty space Wave – a vibratory disturbance that propagates through medium or field; transfers energy without transferring matter Wave Front – continuous points on a wave that are in phase with each other Wave Pulse – a single vibratory disturbance that propagates through a medium or field Wavelength – the distance along a wave between two successive points in phase Wave Speed – the rate at which a wave propagates through a medium or field

Unit 12: Modern Topics Absorption Spectrum – the characteristic set of frequencies absorbed by a gas Alpha decay – the emission of an alpha particle from the nucleus Alpha particle – massive positively charged atomic particle; a helium nucleus Antimatter – material consisting of atoms which are composed of antiprotons, antineutrons and positrons Antiparticle – a particle having mass, lifetime and spin identical to the associated particle, but with charge of opposite sign and magnetic moment reversed in sign Antiquark – the antiparticle of a quark Atom – the smallest particle of an element Atomic number – the number of protons in an atom’s nucleus Atomic Spectrum – a specific series of frequencies of electromagnetic radiation produces when electrons in excited atoms return to lower energy states Baryon – a hadron made up of three quarks

Beta decay - the emission of a beta particle and an antineutrino from the nucleus Binding energy – the energy equivalent of the mass defect; always negative Bright-line ( Emission) Spectrum – a series of bright lines that results from the emission of radiation of specific frequencies by a heated gas Compton Effect – the shift in the energy of scattered photons DeBroglie Wavelength – the wavelength associated with a moving particle Energy level – the quantized amount of energy that an atom may have at each level Energy level diagram – diagram representing the energy levels of a quantized system Excited state – any energy level of an atom that is higher than its ground state Force carrier – particle that transmit, or carry forces between matter Gamma Decay – the emission of a photon from the nucleus Ground state – state of an atom with the smallest allowable amount energy Hadron – a particle made up of quarks, interacts through the strong force Half-life – the time required for half the atoms in a given quantity of a radioactive element to decay Ionization potential – the energy required to remove an electron from an atom Lepton- a particle that interacts through the weak, electromagnetic and gravitation forces Mass defect – the difference between the sum of the masses of the nucleons and the mass of the nucleus Mass number – the number of nucleons in the nucleus Meson – a hadron made up of a quark and an anti-quark Neutrino – a neutral lepton that has energy and momentum, but almost no mass Nucleon – a proton or neutron within the nucleus of an atom Photoelectric effect – the emission of electrons by certain metals when they are exposed to electromagnetic radiation Photon – quanta of electromagnetic radiation, has energy and momentum, but no mass Positron – an anti-electron Quantized – condition that restricts a quantity to discrete amounts, or quanta

Quantum – a discrete packet of some quantity Quantum model – a model for matter and energy using wave properties and quantization Quark – tiny particles that make up hadrons Spectral line – a particular frequency of absorbed or emitted energy Standard model – a model of matter in which all particles can be grouped into three families; quarks, leptons, and force carriers Stationary state – any particular orbit that can be occupied by an electron in an atom Universal mass constant – atomic mass unit equal to 1.66x10-27 kg