Transfer of Thermal Energy 2.3.3

Thermal Energy Transfer

It is a hot summer day, so Mattie poured herself some lemonade. The lemonade was warm, so she added ice to the glass. After 10 minutes, she noticed the ice was melting and the lemonade was cold. She wondered what made the lemonade get cold. She had three ideas:
1- coldness from the ice moved into the lemonade.
2- heat from the lemonade moved into the ice.
3- coldness & heat moved back and forth to make lemonade cold

​Problem Solving

Poll

What do you think caused the lemonade to get cold?

• coldness from ice moved into the lemonade

• heat from the lemonade moved into the ice

• coldness & heat moved back and forth to cool it

• None of the above

​from the Latin conducere which means to lead or bring together

Two object transfer energy through touching

​​Conduction

​From Latin convectio which means the act of carrying


Transfer of energy in a circle

​​Convection

​From Latin radiacion which means act or process of emitting light

Transfer of energy through space in waves - like the Sun

​​Radiation

Heat is the transfer of thermal energy.

Energy moves from one object to another or from one place to another.

Energy can only move from
HOT to COLD

​

​Heat & Thermal Energy

​Notes are on Page 44

Conduction is the transfer of heat by two objects touching

Examples:
- spoon in a bowl of soup
- hand holding a hot cup of tea or coffee
- ice in a drink

Occurs in solids, liquids and gases

Conduction

Convection if the transfer of heat due to molecules moving in a circular motion.

​Ex: warm air rises and pushes the cooler air down and it gets reheated and begins to rise again.
See PIC

Occurs in liquids and gases

​Convection

Radiation is waves of energy moving through space to heat something.

Ex: Sun heating ground and water on Earth

Occurs in liquids & gases

​Radiation

Hotspot

Where is convection occurring while the pot is heating up the water?

Jiffy Pop Popcorn
On the Stove

​​Air Popper

​​Microwave Popcorn

​Three Ways Popcorn Pops!

​What type of heat transfer occurs for each
way to pop popcorn?

Always moves from HOT to COLD until it is BALANCED

​

Heat Transfer

Multiple Choice

Sylvia touched a book and a metal case that both were at 30 degrees Celsius.

What best explains why the metal felt colder?

• metal is a conductor and absorbed heat from her hand but not the book.

• metal case holds ice so the cold went through the case and to her hand.

• the book transferred thermal energy to her hand by convection.

• the book is an insulator, so it produces more thermal energy than the case.

It is a hot summer day, so Mattie poured herself some lemonade. The lemonade was warm, so she added ice to the glass. After 10 minutes, she noticed the ice was melting and the lemonade was cold. She wondered what made the lemonade get cold. She had three ideas:
1- coldness from the ice moved into the lemonade.
2- heat from the lemonade moved into the ice.
3- coldness & heat moved back and forth to make lemonade cold

​Problem Solving

Poll

What caused the lemonade to get cold?

Reevaluate and keep or change your answer.

• The cold from the ice cube moved to the lemonade.

• The heat from the lemonade moved to the ice cube.

• The heat and cold moved back and forth .

• None of the above

Match

Match the example to the type of heat transfer.

• conduction

• convection

• radiation

burning hand when touch hot stove

turning on a fan to cool a room

puddle evaporating on a sunny day

• burning hand when touch hot stove

• turning on a fan to cool a room

• puddle evaporating on a sunny day

In this experiment:
One plant is watered with water
One plant watered with milk
One plant watered with orange juice

​

Prep for
Tomorrow

Dog runs through an obstacle course:
One week he is fed his dog food
One week he is fed chicken
One week he is fed rice

​

Dog & Obstacle Course

​See You
Tomorrow
for our
VIRTUAL LAB!