Where did the energy go?
energy transfer study
Notes based on discoveries based on energy up to this point - and observations of a ball as it's bouncing.
We started out taking notes on what we've learned thus far about energy. The main point that I was trying to make in our notes was that energy is conserved - meaning that energy is neither created nor destroyed.
- First I took a racquetball and had students identify the form of energy as I held it.
- Then I had the students identify the form of energy as it fell.
- Then I caught the ball at the peak of its return - then had them notice something.
- But before I had them respond, I immediately jumped into creating a position over time graph and had students create one in their journal as well.
- I then then informed them that I was going to drop the ball two times. The first time I wanted them to just simply watch. After the second time, they were told to graph the position of the ball over time as it bounced 5 times.
- I then had the students graph it, and a member of their table drew their graph on the back of the room boards.
- After a discussion, I had students make some observations in their books concerning the ball falling and the amount of energy within the system.
- I prompted them that this should be posing a problem with the notes we took. I then challenged them to see if they could figure it out. The problem is that the energy appears to not be conserved.
- Problem identified:
- If energy is conserved, why then did the ball not return back to its original position?
- Where did the energy go?
- If energy is about moving things, what form did this energy take? What does it look like?
- Are there other forms of energy?
- I then had students take the racquet balls and play with them for over 5 minutes to investigate where the energy went and what form did this energy leave the system. In other words, what does this energy look like? What's moving?
- We then posted the answers to the questions on the back boards and discussed it as a class.
- If we had time, students then drew a model of what is occurring with this energy transfer conundrum, and explained it below.
- In addition - students proposed a way to investigate their idea's a little further.
Phenomena:
A ball, after it has been dropped, will rise at a point lower than the original dropping position.
Question:
A ball, after it has been dropped, will rise at a point lower than the original dropping position.
Question:
- If energy is conserved, why then did the ball lose gravitational potential energy (via height?)
- Where did that energy go and in what form?
investigating further
Today, each group of students created at least 3 experiments to investigate where the missing energy goes. Then we had each group share with other members of the class their findings.
If they had a chance, they discussed what other investigations they would conduct - or how does their findings relate to the meteorite impact study or the car crash study?
If they had a chance, they discussed what other investigations they would conduct - or how does their findings relate to the meteorite impact study or the car crash study?
STUDENT EXPERIMENTS ON THE BALL'S MYSTERY ENERGY (Day 2)
Students were challenged to come up with 2 experiments based on their hypothesis and 1-2 experiments based on anything that piques their curiosity. Here are some results of a few of the many experiments that were ran.
STUDENT EXPERIMENTS
motion detector experimentThis student wanted to see if the energy from the ball goes into the table in the form of vibrations. To test this idea out, she put rice on the table to see if the rice shook after the ball hit the table.
Results: the rice shook. They then wanted to see if height of the ball made a difference with the amount the rice shook. Results: it vibrated more when they increased the height. |
wave detector experimentThis student wanted to see if the energy from the ball went into the table by making it vibrate. To test this, he placed a cup of water on the table full of water and looked to see if waves are generated in the cup when the ball hit the table.
Results: The water vibrated. |
surface wave experimentThese students wanted to see if the ball would make waves on the surface of the water if the ball hit a flat surface that was floating on the water.
Results: it created waves on the surface. |
sound experimentThese students were testing to see if the ball makes sound after it hits.
Results: The students heard sound. They then wanted to see if height made a difference with the sound. Results: it got louder when they dropped it from a higher height. |
energy transfer experimentThis student was testing to see if energy from the ball would transfer into the other ball floating in the water - and found out that indeed the floating ball did receive the energy from the falling ball, and got dunked deeper into the water. The ping pong ball in the water represented molecules from the table.
Results: The blue ball made the ping pong ball go down into the cup of water. |
Heat signature experimentThis student was testing to see if either the table or the ball heated up as a result of colliding.
Results: though controversial, the table may have warmed up slightly and so did the ball. Further testing may need to happen. |
Collisions & Friction Between Objects Turns Into Heat
Collisions create heat - and so does friction.
Splatter Patterns experiment
This student was studying the elasticity of the ball as the energy was leaving the system via splatter patterns on the table.
Results: the splatter patterns start out large and progressively get smaller.
Results: the splatter patterns start out large and progressively get smaller.
Squishing Ball Experiment
In this students experiment - he wanted to see how the ball behaved when thrown against the wall - to see if the ball distorts. What we find is that the ball does distort - and for obvious reasons - it rebounds back to its original shape.
BALL OBSERVATIONS (DAY 3) - MAKING THE CONNECTION
- Today, we learned at least 3 things from each group and wrote about it in our journals.
- We then re-drew our model that incorporated all that we learned in our journals.
- Then we added to the model drawn in the front of the room.
- We then discussed the model
- We then pointed out the small connectivity with vibrations and how it related to sound.
- We then discussed what caused sounds and how it worked.
- We then ran a few demos and concluded that vibrations and sounds are the same thing. One influences the other because they are one and the same.
student observations, data analysis & discoveries
Part 1: Students put up key observations & discoveries for their particular groups experiments.
Part 2: As a class - we wrote down & discussed each of the discoveries made.
Part 3: Students used all of this information and fleshed out the initial model of a ball dropping onto a table - by adding elements to the model, and also completing the model in their notebooks.
Part 4: Furthering our discussion & discovery - Are waves and sound the same thing?
This is now the beginning of our waves sound and light investigations.