Heat and WavesChapter 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.