Thermal Energy Review for EC3

Thermal Energy Review

Q3 Test on Thursday!!!

It's all about ENERGY!

• Energy is the ability to do work or cause change.

• Kinetic Energy is the energy of movement.

• The total kinetic energy of all of the molecules of an object is called the thermal energy.

• The average kinetic energy of the molecules of an object is called the temperature.

• SHARE OUT: How do you calculate the average of a set of numbers?

Multiple Choice

The energy of motion is

• movement energy

• kinetic energy

• potential energy

• thermal energy

Multiple Choice

The total kinetic energy all of the particles within a substance is

• temperature

• hot

• thermal energy

• total energy

Multiple Choice

The average kinetic energy of the atoms or molecules within a substance is

• temperature

• kinetic energy

• thermal energy

• water vapor

The faster the molecules of an object are moving, the warmer the object is.

Higher average KE = Higher Temperature

Multiple Choice

Even though sample A has a higher temperature, sample B has a higher thermal energy. Pick the correct explanation from the choices below

• the molecules in sample B are brown and have high energy

• the molecules in sample A are yellow and have low energy

• thermal energy is higher when temperature is lower

• there are many more molecules in sample B which make the total energy higher

Multiple Choice

A large bowl and a smaller mug are both filled with soup. The soup is 145 degrees in both containers. Which has more total thermal energy?

• The bowl of soup

• The mug of soup

• They have the exact same total thermal energy

Multiple Choice

Which sample has the higher temperature?

• Sample B because it has more thermal energy and more molecules

• Sample B because the molecules are brown

• Sample A because the molecules are moving faster and have more average kinetic energy

• Sample A because yellow is such a hot color

Multiple Choice

Which sample has molecules with more average kinetic energy ?

• Sample B, because it has more molecules

• Sample A because it has faster moving molecules

• Sample A because it has yellow molecules

• Sample B because it has brown molecules

SHARE OUT: What happens when two objects with different amounts of thermal energy touch?

Thermal Energy Transfer

• When two objects come into contact, thermal energy transfers between them.

• What does it mean to transfer?

• Thermal energy will ALWAYS transfer from the object with a higher temperature to the object with a lower temperature.

• HOT --> COLD

• How does the picture show this?

Heat transfers until...

• The two objects are the same temperature (have the same average KE)

• When two objects reach the same temperature they are at equilibrium.

• Thermal energy transfer will stop when two objects are stable or at equilibrium.

• The equilibirum will be the average of the two temperatures

Multiple Choice

There will always be heat transfer between two objects that are touching if...

• the temperatures are the same in each sample

• there is a difference in temperature between samples

Multiple Choice

Energy will always be transferred from the...

• hotter sample to the colder sample

• colder sample to the hotter sample

Multiple Choice

Stephen puts a hockey puck onto ice. After a while the temperature of the hockey puck decreases. What happens to the molecules of the hockey puck when the temperature of the puck decreases?

• The hockey puck loses heat molecules.

• The kinetic energy of the molecules in the hockey puck decreases.

• The kinetic energy of the molecules in the hockey puck increases.

• The cold energy of the molecules in the hockey puck increases.

Multiple Choice

If you brought sample A and B close together , in what direction would heat be transferred?

• From sample A to sample B

• From sample B to sample A

• Heat would not be transferred.

• sample A and sample B would both transfer heat to each other.

Multiple Choice

In this picture, heat is being transferred from sample B to sample A. When will the heat transfer stop?

• Heat transfer will keep on until object B has zero thermal energy

• Heat transfer will not stop, it will keep going

• Heat transfer will stop when sample A and sample B have reached the same temperature.

Multiple Choice

Once heat transfer is complete the temperature here will be

• 16 degrees

• 12 degrees

• 10 degrees

• 8 degrees

REMEMBER...

When thermal energy is transfer is happening, molecules are transferring KE from on object to the other. The molecules of the object will stay the same, just their energy will change!

In this example...

What is happening to the energy of the molecules in Sample A?

What is happening to the energy of the molecules in Sample B?

After the transfer...

The energy stopped transferring between Sample A and B because they reached equilibrium. They're now the same exact temperature.

Why does Sample B have more Thermal Energy if it is the same temperature as Sample A?

What would happen if I added more KE to Sample A by holding a flame under it?

Poll

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Poll

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