Cat-Traption and the Conservation of Energy

1. The teacher will show the animation to the whole class.

Complete Run Through (Flash Required)

http://www.learner.org/workshops/energy/cattraption/catrunthru.html

2. As the students watch the animation, they will observe the movements of the Cat-Traption and create a list of the movements on a teacher created document with the diagram from the animation (see the Advanced Preparation Section for the diagram). The student will name the item and what caused it to move (see list below). Students' answers may not be identical to those used below and the animation may need to be played more than once.

1. Tug on tether caused by cat moves stick on a pivot
2. Stick knocks the tethered ball off a pedestal
3. Ball drops and swings
4. Ball knocks steel ball #1
5. Steel Ball #1 knocked into steel ball #2
6. Electric switch turns on the electromagnet
7. Movement of metal plate releases cup
8. Cup rises on spring
9. Rising of cup releases toy mouse
10. Solar cell operates an electric motor
11. Electric motor turns a wheel with projecting rod
12. Rod turns the wheel a bit more with each turn
13. Axel reels in the string

THIS PART IS NOT CLEAR IN THE ANIMATION WITH THE QUESTIONS

1. String pulls sponge from beneath end of a sealed bag
2. As the end of the bag drops, water flows onto Alka-Seltzer tablets
3. Tablets fizz, inflating the bag
4. Inflation of the bag tips over the box of cat food
5. Tipping of the box causes the cat food to spill
6. Cat eats food from the bowl

3. Within their groups, or in pairs, the students will compare answers and make adjustments as needed.

4. Next, return to the animation, and as a whole group, move through the animation again. Read the questions aloud as the students write their responses on the same sheet of paper (found in the Cat-Traption Activity section). After they make their selection from the multiple choice questions A-E, have them to explain their answer. Before moving on to the next question, poll the class to gauge their understanding and then show the correct answer and explanation. Instruct the students to make corrections as needed. Continue in this manner until all questions have been assessed.

Correct Answers for A-E

 The Sun- The cat's food source came from grain which received its energy from the sun.

B. Not all the energy of the first ball causes the second ball to roll. What happened to the rest of the energy?

Both of the above- (A. It is converted to heat and B. It is converted to sound)-Energy is never used completely up, some is converted to heat, and some is converted to sound.

C. What energy causes the cup to rise, releasing the mechanical mouse?

Elastic potential energy from the spring-The spring has potential energy when it is compressed and when it is stretched it has kinetic energy causing the cup to rise.

D. What conditions would reduce the amount of energy transferred from the solar cell to the motor?

All of the above (Raising the lamp higher above the solar cell, Moving the solar cell partially out from under the lamp, or Using a dimmer bulb in the lamp)

E. Did the cat feed itself?

No, because people set up the Cat-Traption that fed the cat.

Answers may vary.

 5. Once the students have completed the questions, they will use the diagram and label five energy transformations.

6. Finally, the teacher will give each student a note card. On the front of the note card the student will:

• Define the Conservation of Energy
• Define Kinetic Energy 
• Provide an example of an energy transformation.
• On the back of the note card, the student will illustrate the example and label the transfer of kinetic energy. (roller coaster, bowling, pool, etc.)