TEKS 7.8 AThe Force is with You!

TAKS Objective 4 – The student will demonstrate an understanding of motion, forces, and energy.

Learned Science Concepts

1. Unbalanced forces cause changes in the speed or direction of an object’s motion.

2. Waves are generated and can travel through different media.

TEKS 7.8 Science conceptsThe student knows that complex interactions occur between matter and energy. The student is expected to:

(A) Illustrate examples of potential and kinetic energy in everyday life such as objects at rest, movement of geologic faults, and falling water.

OverviewThe students will examine the relationship between kinetic and potential energy. They will use experimentation and data collection to see that kinetic energy is a function of mass and velocity. They will also examine how potential energy is changed due to condition and position.

Instructional StrategiesHands-on activities will involve discovery, inquiry, and experimentation. The activities scaffold learning concepts to strengthen concepts of force and motion. Students will begin studying linear motion in a nearly frictionless environment. They will apply a force and measure results. They will next look and unseen forces due to air resistance. Finally they will use the concept of air resistance to study and explain terminal speed in a freefall. A second series of exercises will allow students to study two-dimensional motion where one direction experiences the constant force of gravity. Counterintuitive ideas will be used to dispel deep-set misconceptions of motion.

Objectives1. The learner will illustrate real-world examples of potential and kinetic energy.

2. The learner will simulate how pressure affects layers of rock in an earthquake by applying pressure horizontally to layers of clay to increase potential energy.

3. The learner will determine if potential energy due to height above the earth will affect kinetic energy of an object.

For Teacher’s Eyes OnlyConcepts & Vocabulary

Energy – the ability to cause changeMatter – Anything that has mass and volumeKinetic energy – the energy of motion; kinetic energy depends on speed and massPotential energy – stored energy due to position or conditionMass – the amount of matter in a substanceVelocity – the speed of an object in a particular direction

Kinetic energy = ½ mass x velocity2

Potential energy = weight x height

Energy is the ability to cause change. It is also often defined as the ability to do work. In any case energy is the stuff that allows the world to be animated. If it were not for energy, the world be like a picture with no motion or action of any kind.

All energy is divided into two basic categories: kinetic and potential. The word, kinetic is derived from the Greek root word “ kinein” which means “to move”. Potential comes from the Latin word “potere” which translates as “to be powerful”. These are not really forms of energy as much as states of the different forms of energy.

For example, the forms of energy are heat, light, sound, chemical, atomic, electrical, and mechanical. Heat can be either kinetic or potential. If a light bulb is not turned on, but it has the ability to produce light, it has a potential energy in the filament. When electricity runs through the filament causing it to heat up, the energy then becomes kinetic because light is actually being produced.

If you hold a rock in the air, it has potential energy to move. It could either be dropped or thrown. Either way a force acts on the rock to produce motion. The force could be gravity, which pulls objects down to the earth, or it could be mechanical energy from your hand moving it.

Potential energy exists either because of an object’s condition or its position. Any matter can have stored energy. A boulder sitting on the edge of a cliff has potential to fall due to its position or height above the earth. A wind-up toy has potential energy due to its condition of being wound up. A piece of wood has stored energy because of its ability to burn. All energy starts out as potential energy.

The amount of potential energy an object possesses depends on its height above the earth and its weight. The higher it is, the more potential energy is has. The heavier it is, the more potential energy it has.

Kinetic energy occurs when potential energy is used or transformed into kinetic energy. Kinetic energy can also be transferred from one object to another. When a bat is swung to hit a ball, the kinetic energy of the bat is transferred to the ball.

Kinetic energy is determined by the mass of the object and the velocity at which the object is moving. If two objects are moving at the same velocity but one has twice the mass of the other, the object with double the mass has double the kinetic energy.

Student Misconceptions Misconception

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Rebuild Concept

Misconception

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Student Prior Knowledge

5 E’s

EngageDemonstration: Come back can

The Come Back Can may be made of an oatmeal box with lid. A lead fishing sinker is attached to the center of a rubber band with a piece of string. Cut a tiny opening in the center lid and bottom of the box. Pull one end of the rubber band through the hole in the bottom of the box and fasten it to the outside with a paperclip. Pull the rubber band through the inside of the box, then through the hole in the lid and fasten it to the outside of the lid with a paper clip. Using some books, elevate a board (about 1 meter long). Place the box on its side at the top of the board and ask what kind of energy the box possesses. (Potential due to position) Then let the box roll down the board. Ask what kind of energy the box now has. (Kinetic due to the motion) It should roll, then almost stop, then begin to roll back the other way. Have the students explain what they think happened, then explain that the rubber band is winding up inside and giving the box potential energy due to its condition of being wound up so that it can then have the kinetic energy to move back in the opposite direction.

ExploreExploration 1

Activity: Illustrate the MomentClass Time: 30 minutesObjective: The learner will illustrate real-world examples of potential and kinetic energy.Materials:

Blackline Master: Student Worksheet – Illustrate the Moment (Exploration 1)

Drawing paperColored pencils or crayonsStudent Information Sheet

The students will illustrate examples of kinetic and potential energy. They will divide their paper into two sections, then draw and label an example of potential energy on one side and an example of kinetic energy on the other side. The pictures should be displayed on the walls around the room to encourage students to think of many examples in the world around them of kinetic and potential energy.

Exploration 2Activity: Break It Up!Class Time: 15 minutesObjective: The learner will simulate how pressure affects layers of rock in an earthquake by applying pressure horizontally to layers of clay increasing potential energy.

Materials:

Blackline Master: Student Worksheet – Break It Up! (Exploration 2)Dry sticksModeling clay in different colorsNewspaper to protect the work area

Students will simulate how potential energy builds up by the horizontal application of pressure to layers of clay. They will observe how even a seemingly rigid object (a dry stick) can bend before it breaks. Then they will form layers of clay from different colors and observe how applying pressure from the ends (simulating the lateral pressure that occurs on tectonic plates) will first cause the layers to bend, then break.

Summary Questions – Answer Key

1. Identify the potential energy from the activities above. Potential energy existed in the stick both as potential heat energy because it will burn and as pressure was applied to each end of the stick producing unbalanced forces. Potential energy existed in the clay layers as pressure was applied to each end of the clay producing unbalanced forces, thus motion (the bending of the clay)

2. Identify the kinetic energy from the activities above. Kinetic energy was produced when the stick began to bend. Kinetic energy was produced when the clay began to bend or change shapes as well.

3. How does this simulation illustrate what happens to layers of rock when lateral pressure is applied? When layers of rock are under pressure either horizontally or vertically, eventually motion will occur in order to release the pressure. This energy of motion is of course kinetic energy and results in a fracture in the rock,

which may push together or pull apart, depending on the direction of the pressure. There are several types of fractures that may occur.

4. Based on your observations in this activity, explain how earthquakes may occur.Earthquakes are a result of the build-up of pressure either under the earth pushing up vertically (as when rock becomes superheated and begins to expand), or laterally when one plate puts pressure on another plate.

Explain

Potential energy exists in all matter and all energy begins as potential energy, which may become kinetic energy. Potential energy exists either because of an object’s condition or its position. Any matter can have stored energy. A boulder sitting on the edge of a cliff has potential to fall due to its position or height above the earth. A wind-up toy has potential energy due to its condition of being wound up. A piece of wood has stored energy because of its ability to burn. All energy starts out as potential energy.

The amount of potential energy an object possesses depends on its height above the earth and its weight. The higher it is, the more potential energy is has. The heavier it is, the more potential energy it has.

Kinetic energy occurs when potential energy is used or transformed into kinetic energy. Kinetic energy can also be transferred from one object to another. When a bat is swung to hit a ball, the kinetic energy of the bat is transferred to the ball.

Kinetic energy is determined by the mass of the object and the velocity at which the object is moving. If two objects are moving at the same velocity but one has twice the mass of the other, the object with double the mass has double the kinetic energy.

ElaborateElaborate1

Experiment: High RollerClass Time: 15 minutesObjective : The learner will determine if potential energy due to height above the earth will affect kinetic energy of an object.

Materials (per group):

2 chairsMasking tape Meter stickOne marbleOne eight-foot section of vinyl ceiling molding

Activity Overview : The students will divide into groups of four. They will tape one end of an eight-foot section of vinyl ceiling molding to the back of one chair and tape the other end of the molding to the back of another chair. The molding should form a curve between the two chairs that drops down far enough to just touch the floor. The marble should be placed at different heights on the ramp (molding) then allowed to free-fall down the ramp. The height reached on the other side of the ramp will be recorded for each drop height. The students will then determine if the potential energy due to position (height) has an affect on the kinetic energy of the marble.

KEY:

Values may vary, but the height the marble reaches on the other side of the ramp (on the first roll) should be very close to the height it was dropped from.

Summary Questions:1. The greatest potential energy is at the highest drop position.2. The greatest kinetic energy is at the bottom of the ramp.3. Yes. The marble losses potential energy as it nears the floor, but has it all the way

down even as it is falling. It then gains potential energy again as it moves higher up the other side. So essentially, the marble possesses both kinetic and potential energy as soon as it is dropped. Only at the floor is the potential energy due to gravity, at “0”.

Elaborate2

Experiment: Mass in MotionClass Time: 45 minutesObjectives:

1. The learner will determine if mass of an object affects kinetic and potential energy of that object.

2. The learner will determine if potential energy due to height above the earth will affect kinetic energy of an object.

Materials (per group):

4 meter sticks4 books of equal size

2 steel balls of equal size but different masses2 identical cardboard boxes (approximately 10 cm on the sides)

Activity Overview :

Students will determine if mass affect the kinetic energy of an object by using two steel balls that will hit a box and cause it to move when rolled down a ramp. The kinetic energy of the ball is transferred to the box and measured by the distance the box moves. The students will then determine whether of not gravitational potential energy will affect kinetic energy of a ball by again rolling a ball down a ramp and observing how far a box is moved.

KEY: Questions:

1. When did the balls possess potential energy? At the top of the ramp2. When did the balls possess kinetic energy? When the ball began to move3. When did the box possess potential energy? When sitting at the bottom of the

ramp.4. What gave the box kinetic energy? The kinetic energy of the ball was transferred

to the box5. How would you explain why the box moved in terms of potential and kinetic

energy? The box had potential energy sitting on the floor. The ball gave it kinetic energy when it hit the box.

6. Compare the distance the two balls moved the box. The ball with greater mass will move farther.

7. Did both balls possess the same amount of potential energy? Why or why not? The ball with greater mass had a greater potential energy

8. Did both balls possess the same amount of kinetic energy? Why or why not? The ball with greater mass had greater kinetic energy due to its mass

9. Were the balls traveling the same speed? How can you tell? Yes. They move the same distance in the same amount of time.

Questions:

1. Compare the distance the box travels with each change in ramp height. The box travels a greater distance with each increase in ramp height.

2. Was kinetic energy of the ball affected by ramp height? How do you know? Yes. The box was moved a greater distance each time the ramp height was increased.

3. Was potential energy of the ball affected by ramp height? How do you know?Yes. As the height of the ramp increased, the potential energy also increased because it resulted in greater kinetic energy.

Elaborate 3

Experiment: Kinetic MouseClass Time: 45 minutesObjectives:

Materials (per group):

Activity Overview :

EvaluateEnergy – Potential or Kinetic?

Number your paper from 1-20 and label each of the following as K for possessing kinetic energy or P for possessing potential energy.

1. a moving skateboard2. a rock at the edge of a cliff3. a glass of milk4. gasoline in a car tank (car is not on)5. a basketball passing through the hoop6. a dry cell of a battery7. an acorn hanging from an oak tree8. a person climbing a ladder9. a piece of celery10. blowing wind11. a waving hand12. a wound up music box that is closed13. a flowerpot sitting on a windowsill14. a foot kicking a football15. a lump of coal16. a running man

17. a burning candle18. a stretched rubber band19. a firecracker that has not been lit20. a moving car

KEY:

1. K2. P3. P4. P5. K6. P7. P8. K and P – the person is moving so he possesses kinetic energy but as he goes

higher on the ladder, he increases his potential energy due to height above the ground.

9. P10. K11. K12. P13. P14. K15. P16. K17. K and P – the candle wax and wick both possess potential energy until they are

gone. The fire is the kinetic energy of both heat and light.18. P19. P20. K

Student Worksheet Illustrate the Moment

Exploration 1

Student Information:

All forms of energy (heat, light, sound, mechanical,…) exist in two ways: potential or kinetic. Potential energy is stored energy. It is found in all matter and all energy begins as potential energy. The second way energy exists is in the form of motion. Then it is called kinetic energy. Any time you see something move or interact in any way, kinetic energy is being used.

Kinetic and potential energy are all around you every day. Food contains potential energy. When we eat it, the energy can be converted into a form we can use to carry on all daily activities even down to a cellular level. A book sitting at rest on a table

has potential energy because if it falls off the table, motion occurs (kinetic energy). Anything moving has kinetic energy: a car riding down the road, a roller coaster, a waterfall, chemical reactions, etc.

Objective: The learner will illustrate real-world examples of potential and kinetic energy.

Materials:Drawing paperColored pencils or crayonsStudent Information Sheet

Procedure:

In this activity, you will draw pictures of examples you can find around you of kinetic and potential energy. Divide your paper into two sides. On one side, draw, color, and label an example of potential energy. On the other side do the same with an example of kinetic energy. You may want to check your idea with your teacher or another student before you begin drawing.

On the back of your paper, put your name, date, and period # and tell how your drawings illustrate kinetic and potential energy.

Student Worksheet Break It Up!Exploration 2

Forces are constantly pushing and pulling on the earth’s crust. The earth’s crust, which continues from dry land to the land under the sea, is thought to be composed of several really large “plates” of earth. These plates are constantly moving even though those motions are not obvious to us. There are also huge cracks within the plates called fault lines. As the cruse floats on the layer beneath it, called the mantle, pressure is created horizontally. If pressure becomes great enough between plates or at fault lines, the earth will bend and may eventually crack causing an earthquake. In this activity, you will be using dry sticks and clay to simulate what happens to layers of rock when pressure is applied laterally. Then you will make inferences about what causes an earthquake.

Objective: The learner will explain the results of applying a pressure horizontally to layers of clay increases potential energy which when pressure is sufficient becomes the kinetic energy of motion in order to simulate how pressure (potential energy) affects layers of rock in an earthquake.

Problem 1: Will a dry stick bend before it breaks?

Problem 2: What affect will applying horizontal pressure to each end of several layers of clay stacked on top of each other have on the layers?

Materials:

Dry sticksModeling clay in different colorsNewspaper to protect the work area

Procedure:

Part 1

Take the dry stick and hold it at each end. Find out if a dry stick will bend before it breaks. Record your observations here.

Part 2

Using the clay, flatten out several layers of different colors and place them on top of each other. Placing your hands at each end, push the layers together horizontally. Record you observations here.

Summary Questions

1. Identify the potential energy from the activities above.2. Identify the kinetic energy from the activities above.

3. How does this simulation illustrate what happens to layers of rock when lateral pressure is applied?

4. Based on your observations in this activity, explain how earthquakes may occur.

High RollerElaborate 1

Objective: The learner will determine if potential energy due to height above the earth will affect kinetic energy of an object.

Problem: How does potential energy due to position (height above the earth) affect kinetic energy of a marble to roll back up a curved ramp?

Materials (per group):

2 chairsMasking tape Meter stick

One marbleOne eight-foot section of vinyl ceiling molding

Procedure: Part 1

1. Place two chairs, back sides facing each other, about 3 meters apart. 2. Using the masking tape, tape one end of the vinyl molding to the top back of one

chair and the other end to the top back of the other chair.3. Adjust the distance between the two chairs so that the molding ramp just touches

the floor. Then tape the sides of the ramp to the floor.4. Place the marble on the floor in the center of the ramp. What is the potential

energy of the marble due to gravity?5. Now hold the marble against side of the ramp 10 cm above the floor and release it

carefully. How far does the marble travel up the other side? (Measure the distance from the floor the marble travels up the other side of the ramp.) Enter this information into your data table.

6. Repeat step 5 at 20 cm, 30 cm, 40 cm, and 50 cm. Each time record your data on the data table.

Data Table – High Roller

Height of marble upon release

Height marble travels up other side of ramp

Part 2

Meter stick

Using the data you collected, graph the information. What is your dependent variable? your independent variable?

Summary QuestionsPart 3

1. When does the marble have the greatest amount of potential energy?2. When does the marble have the greatest amount of kinetic energy?3. Does the marble ever possess both kinetic and potential energy? If so when?

4. Based on the graph of your data, how would you describe the relationship between kinetic and potential energy of the marble?

Mass in MotionElaborate 2

Problem: Does mass affect the kinetic energy of an object?

Materials:

4 meter sticks4 books of equal size2 steel balls of equal size but different masses2 identical cardboard boxes (approximately 10 cm on the sides)

Part 1

Procedure:

1. Cut one end and one side out of each box.

2. Create a ramp by taping two meter sticks side by side so that there is a groove in the middle to support the steel ball. Elevate the meter sticks by using three books. (You will have two set-ups: one with one steel ball and the other with the steel ball of a different mass.)

3. Place a box at the lower end of each ramp to catch the ball when it rolls down the ramp.

4. To release the marbles, place a ruler across the top of the meter sticks just below the marbles, then quickly remove the ruler.

5. Measure the distance each box travels and enter it into your data table.

6. Return the boxes to their original position and repeat two more times.

7. Average your results.

Distance box traveled Ball with smaller mass

Ball with larger mass

Trial 1

Trial 2

Trial 3

Average distance the box was moved

Cut out one end.

Cut out one side (bottom is open).

Questions:

10. When did the balls possess potential energy?11. When did the balls possess kinetic energy?12. When did the box possess potential energy?13. What gave the box kinetic energy?14. How would you explain why the box moved in terms of potential and kinetic

energy?

15. Compare the distance the two balls moved the box.

16. Did both balls possess the same amount of potential energy? Why or why not?

17. Did both balls possess the same amount of kinetic energy? Why or why not?

18. Were the balls traveling the same speed? How can you tell?

Conclusions:

Part 2

Using the same set up as in part 1, choose one ball to test. This time change only the height of the ramp starting first with two, then three, then four books.

Distance box travels when struck by marble

Two books Three books Four books

Trial 1

Trial 2

Trial 3

Average distance box moves

Questions:

1. Compare the distance the box travels with each change in ramp height.2. Was kinetic energy of the ball affected by ramp height? How do you know?3. Was potential energy of the ball affected by ramp height? How do you know?

Conclusions:

1.

Problem: To construct a mouse toy that will move across the floor based on the amount of potential energy stored in a twisted rubber band.

Materials: Craft foam (9” x 12”) String (1 meter)

Duck tape the same color as the foam

Small curtain ring (2 cm diameter)

Pattern

Large wooden spool

Scissors

Drill with 5/64” drill bit

Glue

Rubber band slightly longer than length of spool

Craft eyes

Wire coat hanger

Wire cutter

18 gauge floral wire stick

Procedure:

1. Using the pattern, cut out the pieces of the mouse from craft foam. 2. Tape the top sections of the mouse together with small strips of duck tape. Leave

a 2 cm opening for the string to come through.

3. Connect the tail with glue or staple it on. 4. Glue the ears and eyes on. 5. Cut a section of coat hanger wire and bend it according to the shape of the pattern.

Duck tape Craft foam

Drill a small hole through the center of the wooden spool.

2. Insert the rubber band through the large center hole of the spool.

3. Insert a small wire into the drill hole making sure it goes through the center of the rubber band.

4. Bend the ends of the wire flush with the spool and tape them down securely with the duck tape.

5. Hook the ends of the coat hanger wire to each end of the rubber band.

6. Tie a string around the spool and wrap it around and around until you only have enough string left to exit the mouse’s body at the top and tie the end to the curtain ring.

7. Connect the wire and spool apparatus to the mouse body with duck tape. (Before attaching, notice which direction the spool will move when you pull the string and twist the rubber band inside, or your mouse will move backwards)

8. Pull the curtain ring through the hole in the top of the mouse body.

9. Now set the mouse on the floor, pull the string and let her go.

Questions:1. What is potential energy?

2. What is producing potential energy in the mouse?

3. Can the amount of potential energy be increased? Decreased? If so, how?

4. What simple machine is represented in the mouse?

5. Will changing the size of the spool, change the distance the mouse travels? Is so, in what way?

6. What is kinetic energy?

7. How is kinetic energy displayed in the model of the mouse?

Energy – Potential or Kinetic?

Number your paper from 1-20 and label each of the following as K for possessing kinetic energy or P for possessing potential energy.

1. a moving skateboard2. a rock at the edge of a cliff3. a glass of milk4. gasoline in a car tank (car is not on)5. a basketball passing through the hoop6. a dry cell of a battery7. an acorn hanging from an oak tree8. a person climbing a ladder9. a piece of celery10. blowing wind11. a waving hand12. a wound up music box that is closed13. a flowerpot sitting on a windowsill14. a foot kicking a football15. a lump of coal16. a running man17. a burning candle18. a stretched rubber band19. a firecracker that has not been lit20. a moving car