Transformation of Energy Part 2: Heat Energy

Transformation of EnergyPart 2: Heat Energy

Key Learning: Energy is all around us, comes in different forms, and can change from one form to another.

Unit Essential Question: How does energy move from one object to another object?

Concept: Heat Energy

Lesson Essential Questions:1. How are heat energy and temperature related?2. What happens when an object gains or loses heat?3. How do radiation, conduction, and convection transfer heat from one place to another?VocabularyHeat EnergyTemperatureParticle ModelConductionConvectionRadiation

You will be able to answer these questions by the end of Part 1

You should already know what these words mean. You will be able to use them in your responses and discussions throughout the unit



Complete Warm Up #1: You’re riding your bicycle down the street and have to slam on the breaks. You see that you left a black tire mark on the sidewalk. What type of energy transfer/transformation is this evidence of? How do you know?

Transformation of EnergyPart 2: The flow of Energy

A Quick Review of the Particle Model

When energy is transferred to a substance (or is heated up, which is the same thing), the particles become less dense,

vibrate faster (become more excited), and spread out. This is the case with all substances. When a substance cools down or loses energy or energy is transferred away, the opposite is true. The

particles become less excited, more dense, and their bonds become stronger.

Energy Increase

Energy Decrease



INVESTIGATION #3: Smoke SignalsTRANSFORMING KINETIC ENERGY INTO HEAT ENERGY

GOALS: In this investigation, you will …• Observe what happens when large quantities of kinetic energy are

transformed into heat energy, and this heat energy is concentrated in one part of an object.

• Recognize that forces are not energy, they are the mechanism by which energy is transferred in a system

• Look at the role that forces play in the transfer of kinetic energy, and its transformation into heat energy.

INVESTIGATION OVERVIEW: A synopsis of this lesson is as follows…This is the first, and possibly the most dramatic investigation of the heat energy component of the TOE unit. By illustrating the transfer and the transformation of kinetic energy into heat energy, this investigation bridges the investigations of the energy of large moving objects (balls, cups, bottles, etc.) and the investigations of the kinetic energy of particles, the heat energy. Distinguishing between the organized kinetic energy of the moving rope and the random kinetic energy of the particles of the rope and wooden dowel is the primary goal of this investigation. This distinction is made by looking at the different effects that both types of energy have on the properties of the objects involved.


This is what you’re set up should look like. Follow the procedure. Reminder: do not use short quick pulls, use long, even pulls! Keep the rope IN THE SAME SPOT ON THE DOWEL!


1. Why didn’t the cup show signs of heat energy transformation even though our studies have led us to discover that all energy transfers and transformations involve heat being transferred?

2. Use the Particle Model to explain why it is important to keep the rope sliding across the same spot on the dowel if you expect the dowel and rope to get hot enough to start burning.

3. How does kinetic energy transforming to heat energy affect the molecules of an object or substance?

Investigation Analysis


Complete Summary #1: Rubbing your bare hands together creates friction, transforming kinetic energy into heat energy. What is one way you could reduce the friction so that you did not transform as much kinetic energy into heat energy?

Try it out… Were you right, did you reduce the amount of heat energy?


Homework Assignment #4In the Transformation of Energy reading and

assignments…

Read pages 10-11 and complete the assignment on

page 12


Complete Warm Up #2: Think of an example where an increase in energy would cause the molecules of an object to change. (You cannot use an ice cube or wood rod!)


Investigation #4: Heat Energy and Temperature: THERE IS A DIFFERENCE!

GOALS: In this lab investigation, you will …• Observe that there is a difference between the heat energy transferred to an object

and the change in temperature that results from this transfer of energy.• Learn how the mass of a substance influences how much its temperature will change

when it receives heat energy. • Learn that different substances respond differently when they absorb energy. INVESTIGATION OVERVIEW: A synopsis of this lesson is as follows…Tea candles will be introduced as sources of heat energy. We will assume that the tea candles burn identically. We will also assume that each of the tea candles burns uniformly, so that it produces the same amount of heat energy each minute it burns. The first step in the investigation is to make an energy chain describing where the heat energy produced by the candle comes from. Then the class will divide into five groups. Two groups will use candles to ‘heat up’ 100 grams of water, two other groups will ‘heat up’ 200 grams of water, and the fifth group will ‘heat up’ 200 grams of sand. Groups that are working with 100 grams of water will separate and use either 2 or 4 candles to ‘heat up’ their water. The groups working with 200 grams of water will divide up in the same way, and the group working with the sand will use 4 candles. Each group will measure and record how the temperature of their substance changes over a 6 minute period. The class will then share their results and look for patterns in the results.


Pick a Hypothesis…


Here is the progression of how your set up will look. Please follow the procedure and all safety rules, especially since there will be hot wax and open flames.

100ml Water2 candles




200g Sand4 candles

Initial Temperature

1 minute

2 minutes

3 minutes

4 minutes

5 minutes

6 minutes

Change in Temp



Complete Summary #2: In the backyard of a house, there is a large pool, a kiddie pool, and a sandbox. The sandbox and kiddie pool have the same amount of substance. Which of the three will heat up quicker? Explain your reasoning.


Complete Warm Up #3: I have two cups of water. One is 10°C and the other is 100°C. Draw what the particles look like in each cup.

10°C 100°C


INVESTIGATION #5: Mixing and MeltingHEAT ENERGY & TEMPERATURE II

GOALS: In this investigation, you will …• Predict and observe what happens to the final temperature of water when known

amounts of hot water are mixed with known amounts of cold water.• Use the data you collect and the Particle Model to build a better understanding of

heat energy and temperature.• Learn about and describe what is meant by thermal equilibrium.• Study the melting process by melting ice. INVESTIGATION OVERVIEW: A synopsis of this lesson is as follows…The investigation begins with the review of heat energy and temperature changes as viewed through the Particle Model. In this investigation, two samples of water having different initial temperatures will be mixed together, and we will make predictions about the outcome of the mixing process. In the previous investigation, heat energy was added to the samples of water by burning candles. Here, there are no burning candles. All of the heat energy is added to the water samples before they are mixed. We will see that the final temperature of the mixed samples depends on their initial temperatures and their masses. The concept of thermal equilibrium will be introduced to answer the question “When is the mixing done?” Finally, we will mix hot water and ice to see if the solid water (ice) at 0°C behaves differently from liquid water at 0°C.


Investigation Analysis

1. How would you respond to the following argument made by one of your classmates? “When the hot water was mixed into the cold water, the cold in the cold water canceled the heat in the hot water, and the mixture ended up warm.”

2. Rubbing alcohol has a lower boiling temperature than water (meaning it changes phases at a cooler temperature). If you place rubbing alcohol or hand sanitizer on your bare arm, it will quickly evaporate and your skin will feel cool. Why does your skin feel cool? Why can you easily smell the alcohol?


Complete Summary #3: When a hot object and cold object touch, how is heat energy transferred between the two objects?


Homework Assignment #5In the Transformation of Energy reading and assignments…

Read page 13 and complete the assignment on page 14


Complete Warm Up #4: When cooking food on the stove using a pan, the food heats up even though it does not touch the burner. How do you explain this?

Transformation of EnergyPart 2: Heat EnergyThe Definitions

Conduction is the transfer of heat through solids or between two solids that are touching

Convection is the transfer of heat in liquids and gases

Radiation is the transfer of heat through space (no matter is needed for this transfer to occur)

Transformation of EnergyPart 2: Heat Energy1. An old-fashioned radiator heating up a

room

2. Ice cooling down your hand

3. Boiling water by thrusting a red-

hot

piece of iron into it

4. Heat from a fire

5. Hot air rising, cooling, and falling

6. Touching a stove and being burned

7. Heat from the sun warming your

face

8. Heat from a lightbulb

9. Heat from anything else which is

warmer than its surroundings.

The Examples


CONDUCTION:-Touching a stove and being burned

-Ice cooling down your hand

-Boiling water by thrusting a red-hot piece of iron into it

CONVECTION:-Hot air rising, cooling, and falling (convection currents)

-An old-fashioned radiator (creates a convection cell in a room by emitting warm air at the top and drawing in cool air at the bottom)

RADIATION:-Heat from the sun warming your face

-Heat from a lightbulb

-Heat from a fire

-Heat from anything else which is warmer than its surroundings

The Answers


End of Part 2 AssessmentDirections:

In groups of 2 or 3…

You will be creating a poster to represent one of the methods of heat energy transfer.

1. Make a rough draft of a picture to represent the three methods of transfer and have Mr. Herlihy check it. You may not use words except to title the poster.

2. Create your final poster

3. Make it colorful and interesting so it is not boring to look at

Transformation of Energy Part 2: Heat Energy

Documents

Transcript of Transformation of Energy Part 2: Heat Energy