Heat and
Waves
Chapter 10 and
12 Review
Agenda:
Heat
 Temperature, measuring
temperature, and thermal
equilibriium
 Heat transfer is energy
transfer
 Specific heat and
calorimetry
 Latent heat
 Heat transfer
Waves
 Hooke’s Law
 Amplitude, period and
frequency
 Types of waves
 Wave speed
 Interference
 Standing waves
Temperature
 Temperature measures the average kinetic
energy of the atoms or molecules of a
substance.
 Temperature changes when energy is added or
removed.
 All objects attempt to attain thermal equilibrium
by exchanging energy.
Temperature Continued
 Matter expands as temperature increases. This is
called thermal expansion.
 Temperature is measured in (see your formula
sheet for coversions):
 degrees Fahrenheit
 degrees Celsius
 Kelvin
Heat
 Thermal energy is the measure of the TOTAL kinetic
energy of the molecules of a substance
 Heat is the transfer of energy between substances.
 Substances at different temperatures will transfer
energy until they are equal.
 Like all energy, heat can be measured in Joules.
Heat and Work
 Any energy change that cannot be accounted
for by a change in potential or kinetic energy
can be attributed to heat (internal energy) by
way of friction.
Specific Heat
 Different materials require different amounts of
energy to change their temperatures.
 The energy required to raise the temperature of
1 kilogram of a substance by 1 degree Celsius is
its specific heat capacity.
Calorimetry
 Specific heat capacity of
substances can be
determined by calorimetry.
 The amount of energy gained
by the water must equal the
amount of energy lost by the
substance.
Energy during Phase Change
 It takes energy to change phases. TEMPERATURE
DOES NOT CHANGE DURING PHASE CHANGE.
 Latent heat is the energy required to change phase.
 Problem solving: when determining the energy
required to change a substance from one
temperature to another, you must consider if there is
a phase change or not.
Heat Transfer
 Conduction: heat transfer by direct contact
between molecules
 Conductors allow the flow of heat easily
 Insulators inhibit the flow of heat.
 Convection: heat transfer through a fluid
 Radiation: energy transfer through
electromagnetic waves.
Vibration and Waves:
 Hooke’s Law: the restoring force is proportional
to the displacement of the object.
 Displaced objects have potential energy.
 Objects vibrate in simple harmonic motion if they
behave according to Hooke’s Law (pendulums
and mass-spring systems)
Measuring Simple Harmonic
Motion
 Amplitude: the maximum displacement of the
object
 Period: time for one complete cycle (Seconds)
 Frequency: how many cycles completed per
second (Hz)
Pendulums and Mass-Spring
Systems
 Period of a pendulum depends on pendulum
length.
 Period of a mass spring system depends on mass
and spring stiffness.
Wave Types
 Mechanical waves disturb a physical medium.
Non-mechanical waves, like light, do not need a
medium to travel through.
 Pulse waves are a single peak traveling. Periodic
waves are repeated regular motions.
Waves Continued
 Transverse waves are perpendicular to wave
motion.
 Longitudinal waves are parallel to wave motion
Wave Speed
 The speed of a wave is constant for any given
medium.
 Frequency and wavelength are inversely
proportional.
Interference
 When waves collide with each other, it is called
interference.
 If the waves peaks are in the same direction,
they add together for constructive interference.
 If the peaks are in opposite directions, they
subtract for destructive interference.
Standing Waves
 Standing waves can be
generated only at certain
wavelengths relative to the
length of the medium (L).
 2L
 L
 (2/3)L
 (1/2)L
 (2/5)L
 etc.
Homework
 Finish study guide and check solutions.
 Review all slides, and get a good night’s sleep.