Transcript Unit 2: Heat

Unit 2: Heat
Chapter 5
Temperature describes how hot or cold an
object Is.
Facts of Temperature
• Temperature describes how “hot” or “cold”
something is.
• Temperature is the measurement of one
object’s kinetic energy at one specific time.
- energy is the power that enables an
action to take place.
• Temperature is measured in units called
degrees (0o). Scales may be in Celsius,
Fahrenheit or Kelvin.
The Description of Temperature is
Relative
• An ice-cube is warmer than liquid nitrogen, but
both are cold.
vs.
Liquid nitrogen is colder than an ice-cube.
• A burning match is cooler than sun’s surface, but
both are hot.
vs.
The sun is hotter than a burning match.
The Laboratory Thermometer
1000C
37oC
20oC
0oC
•
= Boiling point of water.
= Average human body Temperature
= Room Temperature Range
= Freezing point of water
Any temperatures below 0oC is
referred to as a subzero
temperature
Thermometer
• A thermometer may be used to measure:
- daily temperature of the atmosphere for
accurate weather reporting.
- human body temperature when sick.
- temperature of food for cooking meat.
- temperature of house for comfort.
How Does Temperature affect the
Human body?
Increase of Body Temperature
• When the average body temperature
increases a fever may develop. A fever is
a natural body defense against viral or
bacterial infection. These infections can
not survive the increase of body
temperature.
• Sweating is a way for the body to cool
itself.
How Does Temperature? … cont.
Decrease of Body Temperature
• When the average body temperature
decreases, significantly, hypothermia may
occur.
• Shivering is the body’s natural mechanism
to warm the body by moving.
Types of Heat measuring Devices
• Thermometer
– Thermo means “Heat”.
– Meter means “measuring device”
– Heat measuring device
• Bimetallic Strip
• Thermocouple
• Infrared Thermograph
Some facts on Heat
• Heat is energy
• White light is the hottest
• Heat will always travel to the coldest
object. When you fell something hot, heat
is transferring into you. When you feel
something cold, heat is transferring out of
you.
• Heat is everywhere.
Chapter 5
Scientist use the particle theory of matter to
describe temperature.
The Particle Theory
• All matter is made up of tiny particles
• These particles are always moving – the have
energy.
- The more energy that is added to particles the faster they move.
• There are spaces among particles
• There are attractive forces between particles.
• The particles of one substance differs from the
particles of a different substance.
Energy
Kinetic Energy
vs. Potential Energy
(Energy in Motion)
(Energy at rest)
States of Matter
• Solid
- Fixed Shape
Liquid
Gas
- Changes shape
with container
- Forms a surface
- Changes shape
with container
- No surface
Expansion and Contraction
Thermal Expansion
• The volume of an object of substance increases
as energy (heat) is added to it.
• Particle of matter become active, moving out
from each other
Thermal Contraction
• The volume of an object or substance
decreases as energy (heat) is taken away from
it.
• Particles of matter tend towards inactive.
Changing States of Matter
Changes in Matter - Points
• Freezing point
• Boiling Point
• Melting Point
** Heating Curves **
Chapter 6
Heat is transferred from one place to
another by three different processes
1.)
2.)
3.)
Conduction
Convection
Radiation
Conduction
• Heat is transfered from warmer parts of an
object to more cooler parts via particles.
• Heat from the hot part of the rod closer to the fire
is conducted (travels) to the part of the rod being
held by the hand
Convection
• Process by which moving warm liquid or air
moves/carries heat to other areas.
• Convection current
Radiation
• Heat carries electromagnetic waves of
energy from one location to another.
Solar Radiation
Types of Electromagnetic Waves
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Radio Waves
Microwaves
Infrared Waves
Visible Light
Ultraviolet Waves
X-rays
Gamma Rays
Heating Home
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Solar Energy
Geothermal Energy
Electric Energy
Burning of Fossil Fuels
**Conductors and Insulators
Temperature vs. Heat
• Heat is related to the total kinetic energy
of particles. Heat is the transfer of energy
from a hot object to a colder object.
• Temperature is related to the average
kinetic energy of particle.
Insulators – student examples
Insulators in houses help keep energy in and the
cold out during the winter months. In the
summer insulators help keep the coolness in
and the warmth out.
• Sawdust keeps ice from melting
• Newspaper insulators in attic
• Clothes
• Mud for adobe houses
• Pink, blue or yellow insulation in house
• Feathers in winter jackets
Conductors – student examples
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Steel rod for fire place
Copper tubing
Wire
Cooking pot
Iron frying pan
Kettle pot
Sand