Unit 2: Heat. Chapter 5 Temperature describes how hot or cold an object Is.

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 = Boiling point of water.

37oC = Average human body Temperature

20oC = Room Temperature Range

0oC = 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 Liquid Gas- Fixed Shape - Changes shape - Changes shape

with container with container

- Forms a surface - 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.) Conduction

2.) Convection

3.) 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

• Radio Waves

• Microwaves

• Infrared Waves

• Visible Light

• Ultraviolet Waves

• X-rays

• Gamma Rays

Heating Home

• 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

• Steel rod for fire place

• Copper tubing

• Wire

• Cooking pot

• Iron frying pan

• Kettle pot

• Sand