GSCI 101 Review Sheet Chapter 6 Thermal energy and Thermodynamics Temperature-the quantity that indicates how warm or cold an object is relative to some standard. (degrees) Measure of the average kinetic energy of a particle of the substance Doesn’t depend on the amount of stuff you have. Absolute zero- lower limit of temperature. Heat- energy, specifically the thermal energy that flows from a substance of higher temperature to a lower temperature. (4.18J= 1 calorie; 1000 cal.=1 Calorie) Joule Calorie “calorie” 3 laws of thermodynamics: 1st law of Thermodynamics- “You can never get more ‘work or energy’ out than you put in.” 2nd law of thermodynamics- Heat will never spontaneously flow from a cold substance to a hot substance (that requires work from an outside source) 3rd law of thermodynamics- as a system approaches absolute zero, it will eventually have to draw energy from whatever systems are nearby. Entropy- change measures the dispersal of energy: how much energy is spread out in a particular process, or how widely spread out it becomes at a specific temperature. Specific heat Capacity- of any substance is the quantity of heat required to change the temperature of a unit mass of the substance by 1 degree C. Thermal expansion- Most substances expand when heated (ex. Ball and ring demo) Why wouldn’t you expect all the molecules in a gas to have the same speed? Which of the laws of thermodynamics has exceptions? In the old days, on a cold winter night, it was common to bring a hot object to bed with you. Which would be better to keep you warms through the cold night – a 10 kg iron brick or a 10 kg jug of hot water at the same temperature? Chapter 7 Heat Transfer and Change of Phase Conduction- transfer of heat through contact. Conductors- allows transfer of heat through it Insulators- restricts the flow of heat through it Convection- transfer of heat by the motion of a fluid. Radiation- the transfer of heat by electromagnetic waves. Newton’s law of cooling- Rate of cooling (or warming) proportional to temperature difference- greater the difference in temp the higher the rate of warming or cooling. Greenhouse Effect Heat transfer during a change of phase Evaporation Condensation Sublimation Boiling Freezing/melting What are the 3 common ways in which heat is transferred What makes a good insulator? A good conductor? When you are hot, standing in front of an open refrigerator makes you feel cool. Is the cool air moving to you or is heat moving to the inside of the refrigerator? How does the frequency of radiant energy relate to the absolute temperature of the radiating surface? Explain the Greenhouse Effect. What are the 4 phases of matter? What is evaporation and how is it a cooling process? What is condensation and how is it a warming process? Does a liquid give off energy or absorb energy when it turns into a gas? A solid? Chapter 8 Static and Current Electricity 2 types of charge: Positive (protons, or ions) Negative (electrons or ions) *neutral- balance between + and - Basic law of electrostatics- like charges repel and unlike charges attract Conservation of electric charge- charge cannot be created or destroyed Coulomb’s Law (Electrostatic Force of Attraction)- either a push or a pull Remember: F g = G m1m2/d^2 Electric Field- Area that surrounds a charged object Electric field lines- conceptualization of force fields Electric potential (volts)- energy per charge Electric potential(V) =electric potential energy (J) amount of charge (C) Electric potential energy (joules)- energy due to to position near a larger charge Volt=1 Joule/ 1 Coulomb Electric potential difference (voltage) = electric pressure (ex. Garden hose- difference in electric pressure when level compared to when one side is higher) Electric Current (ampere)- Rate of flow of charged particles Amperage (unit = ampere) DC (direct current)- goes in one direction (ex. Battery) AC (alternating current)- goes one way then another over and over (generated with a generator- 60 cycles per sec or 60 Hz) Electrical resistance-Impedes electrical current Unit = ohm Ω Ohm- resistance unit Superconductor- extremely low resistance Ohm’s law = (current = voltage / resistance) Series circuit-every circuit is connected so one path, if one goes it does not work I=V/R V=IR R=V/I Parallel circuit- multiple paths for electricity to flow. Electric power- The rate at which electric energy is converted into another form of energy Power = current x voltage ; P=IV Unit = Watt What is the charge of a proton, neutron, and an electron? Which has more mass a proton or an electron? Which has more charge? How is Coulomb’s law similar to Newton’s law of gravitation? How is it different? How does the magnitude of electrical force between a pair of charged particles change when the particles are moves twice as far apart? 3 times? ½ times? What is the charge on an electrically polarized object? How is the direction of an electric field defined? What is the difference between electric potential and electric potential energy? How much energy is given to each coulomb of charge passing through a 6 volt battery? What kind of current does a battery produce? AC or DC What kind of current does a generator produce? AC or DC What is the formula for Ohm’s law? What is the function of the third prong on the plug of an electric appliance? Two point charges are separated by 6 cm. The attractive force between them is 20 n. Show that when they are separated by 12 cm, the force between them is 5 N. A certain device in a 120 v circuit has a current rating of 20 A. Show that the resistance of the device is 6 ohms. Show that the current drawn by a 1200 W hair dryer connected to 120 V is 10 A. Chapter 9 Magnetism and Electromagnetic Induction 2 types of magnetic poles: North South *Cannot have one mono pole YET. Basic law of magnetism- like poles repel; opposite poles attract Magnetic field-the region of magnetic influence around a magnetic pole or a moving charged particle. Magnetic domains- clustered regions of aligned magnetic atoms (iron atoms). Electricity and magnetism: a moving charge produces a magnetic field changing magnetic force can induce moving charge *opposite fields are a pull. Electromagnet- a magnet whose field is produced by an electric current. Electric motor (magnetic force on moving charge)- uses magnets to create motion Electromagnetic induction- a changing magnetic field induces a changing electric field Generator-converts mechanical energy into electrical energy. Transformer- change voltage without changing power. P(incoming)=IpVp=P(outgoing)=IsVs (Iv = Vi- steps down or up the voltage If you place a chunk of iron near the north pole of a magnet, attraction occurs. Why does attraction also occur near the South Pole? What fields surround stationary electric charge? A moving charge? Magnet A has twice the magnetic field strength of magnet B, and a a certain distance it pulls on magnet B with a force of 50 N. With how much force, then does magnet B pull on magnet A? At the security area of an airport, you walk through a weak magnetic field inside a large coil of wire. What is the result of a small piece of metal on your person that slightly alters the magnetic field in the coil? How does input and output compare for a generator versus an electric motor? a portable CD player requires 12 V to operate correctly. A transformer allows the device to be powered from a 120 V outlet. If the primary coil has 500 turns, show that the secondary coil requires 50 turns. Chapter 10 Waves and Sound Wave- a wiggle in both space and time. Vibration- a wiggle in time. Wavelength- the distance between successive crests, troughs, or identical parts of a wave. Amplitude-for a wave or vibration, the max displacement on either side of the equilibrium (midpoint) postion. Frequency-for the vibrating body or medium , the number of vibrations per unit of time. For a wave, the number of crests that pass through a particular point per unit of time. Hertz-unit of frequency (1Hz=1 vibration per second) Period-the time required for a vibration or a wave to make a complete cycle (1/ frequency) Wave speed-the speed with which waves passes a particular point wave speed = frequency x wavelength Transverse wave-the medium vibrates in a direct perpendicular to the direction in which the waves travels. (ex. Light, electromagnetic waves) Longitudinal wave-the medium vibrates in a direction parallel (longitudinal) with the direction in which the wave travels (ex. Sound and wave looks like a slinky) Compression- a condensed region of the medium through which a longitudinal wave travels. Rarefaction- a rarefied region, or region of lessened pressure, of the medium through which a longitudinal wave travels. Reflection-the return of a sound wave. an echo Refraction-the bending of a wave, either through a nonuniform medium or from one medium to another, caused by differences in wave speed. Forced vibration- the setting up of vibrations in an object by a vibrating force. Resonance-the response of the body when a forcing frequency matches its natural frequency. Interference- adding two waves algebraically (property of all type of waves) crest to crest-add crest to trough-cancellation Beats- a series of alternative reinforcements and cancellations produced by the interferenceof two waves of slightly different frequency, heard as a throbbing effect in sound waves. Standing wave-a stationary wave pattern formed in a medium when two sets of identical waves passes through the medium in opposite directions. Doppler Effect- the change in frequency of wave motion resulting from motion of the sender or the receiver. Bow waves and sonic booms- examples of the Doppler effect Harmonics = quality Frequency = pitch Amplitude = loudness What is the source of all waves? What is the relationship between frequency and period? What is the mathematical formula for the relationship among frequency, wavelength, and speed? In what direction are the vibrations of a transverse wave? A longitudinal wave? Why does a struck tuning fork sound louder when its handle is held against a table? What kind of waves can interfere? Explain beats. In the Doppler Effect does the frequency of a wave change? What changes?