TEMPERATURE AND THERMAL ENERGY

8TH GRADE

CHAPTER 21 SECTION 1

DO NOW TOGETHER…

With your lab group

•List 5 ways to make yourself feel warmer.

•List 5 ways to make yourself feel cooler.

•GO

OBJECTIVES

Students will…

•Explain how temperature is related to kinetic energy.

•Describe 3 scales used for measuring temperature

•Define thermal energy

WHAT DO YOU ALREADY KNOW ABOUT THERMAL ENERGY?

True/False

Statement

Objects cannot have a temperature below zero on the Celsius scale.

Thermal energy always moves from colder objects to warmer objects.

Thermal energy from the sun reaches earth by conduction through space.

Temperature depends on the kinetic energy of the molecules of a material.

WHAT IS TEMPERATURE?

•Temperature is a measure of the average kinetic energy of molecules.

•Molecules are always moving.

•Energy of motion is called kinetic energy.

•Molecules have more kinetic energy is they are moving faster.

•Which has more kinetic energy: iced tea or hot tea?

THERMAL EXPANSION

Object is Heated

•1)Object becomes warmer

•2) Molecules move faster

•3) Molecules move apart

•4) Object expands

Object is Cooled

•1) Object become cooler

•2) Molecules move slower

•3) Molecules move closer together

•4) Object shrinks or contracts

MEASURING TEMPERATURE-DIFFERENT TEMP SCALES

Characteristics of Each

Scale

Fahrenheit

Celsius Kelvin

Temperature at which water freezes

Temperature at which water boils

Number of degrees between water’s freezing and boiling points

ORGANIZING TEMPERATURE FORMULAS

Fahrenheit to Celsius

Celsius to Fahrenheit

Celsius to Kelvin

Formula C= (5/9)(F-32)

F= (9/5)(C)+32

K= C + 273

Break it down or simplify

[(F-32) x5] / 9=C

[(C x9) /5] +32= F

C + 273=K

PRACTICING TEMPERATURE CONVERSION

•A person’s body temperature is 98.6 F. What is that temperature on the Celsius scale?

•Answer: 37.0 C

•A temperature of 57 C was recorded in 1913 in Death Valley, CA. What is this temperature on the Fahrenheit scale?

•Answer: 134.6 F

THERMAL ENERGY

Potential Energy

• 1) Molecules in a material exert attractive forces on each other

• Ex: Gravity exerts an attractive force on a ball.

• 2) Molecules in a material have potential energy

• Ex: A ball above the ground has potential energy.

• 3) As molecules move closer together or farther apart, potential energy changes

• Ex: As a ball moves closer to or farther from Earth’s surface, its potential energy changes.

FOR NEXT TIME…

•Read pgs. 612-615

•Define heat, conduction and radiation on index cards

•Have test signed by a parent due Thursday.

•Potential and Kinetic Energy