Chapter 10 Heat and Temperature
Download
Report
Transcript Chapter 10 Heat and Temperature
Chapter 10 Heat and Temperature
Define temperature?
A measure of the average kinetic energy of
all the particles within an object.
What happens if the kinetic energy of an
object increases?
The temperature increases
What physical property of substances allows
us to measure temperature accurately?
Objects expand when their temperature
increases
What device is used to measure
temperature?
Thermometer
How does a thermometer work?
As the temperature rises- particles
inside the thermometer gain kinetic
energy and move faster, which causes
the particles in the liquid to move
farther apart causing it to expand
and rise up the tube.
What is absolute zero?
Temperature at which particles no
longer have any energy that can be
transferred.
What are the three types of
temperature scales
Scale
Symbol
Freezing
point of
water
o
32 F
Boiling
Point of
water
o
212 F
C
0oC
100 oC
K
o
273 K
o
373 K
F
Fahrenhe o
it
Scale
Celsius
o
Scale
Kelvin
o
What are the conversion equations for
temperature
Conversion
Written out
Celsius to (9/5 x Celsius) + 32.0
Fahrenheit
equation
(9/5 Tc) + 32
Fahrenheit 5/9 x (Fahrenheit – 32.0) 5/9(Tf-32)
to Celsius
Celsius to
Kelvin
Celsius + 273
Tc + 273
What is heat?
Energy transfer when two objects at
different temperatures interact with
one another
How do you get burned?
Rapid tranfer of energy as heat
Can you get burned from something
cold?
Yes….when you touch a very cold
object, energy transfers as heat from
your skin into the object causing
tissue damage.
What are the three ways that energy
can be transferred?
CONDUCTION: OBJECTS IN DIRECT
CONTACT WILL HAVE TRANSFER OF
ENERGY AS HEAT EXAMPLE: POT ON
STOVE
CONVECTION: TRANSFER OF ENERGY BY
MOVEMENT OF WARM FLUIDS: OVEN
RADIATION:NO DIRECT CONTACT,
DOESN’T INVOLVE THE MOVEMENT OF
MATTER-TRANFER OF ENERGY BY
ELECTROMAGNETIC WAVES: SUN LIGHT
How does conduction work?
Before conduction: the
average kinetic
energy of particles in
an object is the same
throughout
During conduction: the
energy is transferred
from objects to slowly
moving particles
nearby.
How does Convection Work?
During convection, energy is
carried away by a heated gas
or liquid that expands and rises
above cooler, denser gas or
liquid.
The rising warm air is replaced
by cooler, denser air, which
becomes hot and expands and
rises unit it cools contracts,
becomes denser, and sinks
Does convection occur within
solids?
No because particles within solids
are not free to move.
How does radiation work?
• Radiation occurs through electromagnetic
waves in the form of infrared radiation,
visible light, and ultraviolet rays.
• Radiation is the only method of energy
transfer that can take place in a vacuum
What is the difference between
conductors and insulators?
Conductors transfer energy as heat quickly
Solids conduct energy better than liquids or
gas because their particles are packed
closely together.
An exception to liquids as conductors would
be molten or liquid metals which are good.
Metals are better conductors than
nonmetals.
Insulators slow the transfer of energy as
heat.
Wood is a good insulator
What is specific heat?
Describes how much energy is required to
raise an objects temperature.
Is the amount of energy transferred as heat
that will raise the temperature of 1 kg of a
substance by 1 K.
Why do we need to know the specific heat of a
substance?
Predict the effects of larger temperature
changes for masses other that 1 kg
What is the equation for
specific heat?
Energy = (specific heat)
x (mass) x (temp ch.)
Energy= cm∆t
What are 2 principles of thermodynamics?
1. 1st law: Conservation of energy
the total energy used in any process is
conserved
2. 2nd law: Energy transferred as heat
always moves from an object at a high
temperature to an object at low
temperature.