C H 10 H EAT pgs. 357 - 386. T EMPERATURE Adding or removing energy usually changes temperature...
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Transcript of C H 10 H EAT pgs. 357 - 386. T EMPERATURE Adding or removing energy usually changes temperature...
CH 10 HEATpgs. 357 - 386
TEMPERATUREAdding or removing energy
usually changes temperatureTemperature is proportional to the
kinetic energy of atoms and molecules
TEMPERATURETemperature is meaningful only
when it is stableThermal Equilibrium – the state
when two objects in physical contact have identical temperatures
Matter expands as temperature increases (thermal expansion)
MEASURING TEMPERATUREThermometers
Most make use of a change in the volume of a gas or liquid
Most are thin glass tubes containing mercury, colored alcohol, or colored mineral spirits
MEASURING TEMPERATURECalibrating thermometers
requires fixed temperaturesIce point of water – thermometer in
equilibrium with a mixture of ice and water at 1 atm
Steam point of water – thermometer in equilibrium with a mixture of steam and water at 1 atm
TEMPERATURE CONVERSION Temperature in Fahrenheit (TF )
Units are °F Temperature in Celsius (TC)
Units are °C
TEMPERATURE CONVERSION Temperature in Celsius (TC)
Units are °C Temperature in Kelvin (T)
Units are K
HEAT AND ENERGYHeat – the energy transferred
between objects because of a difference in their temperatures
Always moves from the object with the higher temperature to the object with the lower temperature
HEAT AND ENERGY
HEAT AND ENERGYThe transfer of energy as heat
alters an object’s temperatureEnergy transfer depends on
the difference of temperature of the two objects
HEAT AND ENERGYGreater temperature difference =
greater amount of energy transferred
At thermal equilibrium, the net energy exchanged is zero
HEAT (Q)Heat (Q) has units of energy
INTERNAL ENERGY (U)The energy of a substance due to
atomic motionUnits are Joules (J)
INTERNAL ENERGY (U)Internal energy can be changed
through work (friction)The energy required to overcome
friction is transformed into internal energy
Internal energy can also be changed by deforming a solid’s structure Stretching a rubber band or bending
metal
CONSERVATION OF ENERGY
CONSERVATION OF ENERGY
½ mvi2 + mghi = ½ mvf
2 + mghf + ΔU
A device used to demonstrate energy conservation is shown. If a total mass of 11.5 kg falls 1.3 m and all of the mechanical energy is converted to internal energy, by how much will the internal energy of the water increase? (Assume no energy is transferred to or from the surroundings.)