Conservation of Energy lab PDF

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Physic lab...

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Conservation of Energy Name: Svarali Ahire

Objectives 1. To understand transfer between kinetic, potential, and thermal energies. 2. To draw graphs of kinetic, potential, and thermal energy. 3. To understand the effects of friction on energy conservation.

PART A: Use what you already know Before you start using the simulation, you will apply what you know so far about potential, kinetic, thermal, and total energy to predict how these different types of energy will change as a skater rolls back and forth on a half-pipe. Describe the terms listed below in a complete sentence (or complete sentences): Potential Energy The energy contained by an object because of it position relative to other factors. It is basically stored energy in simple terms. Kinetic Energy Kinetic energy is the energy of the object tin motion. Its basically energy possessed by the object due to its motion. Thermal Energy Thermal energy is regarding energy that arises from the temperature possessed within an object mostly due to movement of various particles within. It is also a form of kinetic energy. Total Energy This is the sum of all the energy forms together. It is basically the sum of kinetic and potential energy.

Energy Transfer without Friction If there is no friction, what type of energy does not change? Since there is no friction there won’t be conversion of the kinetic energy into any other form and therefore, the kinetic energy would be the only form and therefore equal to total energy. Total energy does not change.

Energy Transfer with Friction How will the presence of friction affect the skater and the energies you described above? When friction is involved some of the kinetic energy will change to the thermal energy and the total energy will include the thermal and kinetic energy.

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PART B: Half-pipe without Friction You will be investigating different types of energy and how they change using a simulation of a skateboarder on a half-pipe as shown below. Our first investigation will be for the situation without friction. Three points on the halfpipe are labeled: TL (Top Left), Bottom (B), and Top Right (TR).

As shown, all types of energy will be considered zero for the skateboarder at rest on the ground before the event. If the skateboarder is placed on the half-pipe at TL, predict what the Energy Bar Graph will look like. What types of energy will he have at the beginning? Different types of energy will change as the skateboarder begins moving and skates to B, then TR, then back to B, then back to TL. On the Energy Bar Graphs below, predict the amount of each type of energy at that point in the motion. One way to draw your predictions is to use the drawing tools in Word.

TL (start)

B

TR

B 2

TL

PART C: Check your predictions with the Energy Skate Park Basics Simulation Simulation link: https://phet.colorado.edu/en/simulation/energy-skate-park-basics Or type “Energy Skate Park Basics PHET” in Google and click the link. SIMULUATION TIME! Start with the Intro tab. Take some time (~5 minutes) to play with the simulation. Check out all the features! Then use the simulation to check your predicted Energy Bar Graphs in Part B. In another color, fix your graphs. Do NOT erase your original predictions! 1. According to your predictions, what do you think the potential energy of the skater is at the bottom of the half-pipe and what is it at the top left and top right? Explain why. According to my prediction the potential energy of the skater at the top left and at top right are high and equal to the total energy. This is because when the skater is at the very top, he is not speeding and almost slowing down, so his stored energy is higher than the kinetic energy. However as per my prediction the potential energy is almost equal to zero at the bottom of the half pipe. When the skater is at the bottom he is still in speed and has motion therefore the kinetic energy would be higher than the potential energy. 2. Using the energy bar graph, does the simulation agree with your answers? Explain. The simulation’s bar graph is similar to the one I drew in my predictions. However, if I stop the stimulation at the very top (right and left) then the potential energy is very high like showed in my predictions, however at the bottom the kinetic energy is very high but the potential energy is not zero, there is a little bit of potential energy still present. I didn’t show a little bit of potential energy in my predictions, I showed zero potential energy. 3. According to your predictions, what do you think the kinetic energy of the skater is at the bottom of the half-pipe and what is it at the top left and top right? Explain why. The kinetic energy of the skater at the top right and top left is zero. That is because the skater is slowing down here and doesn’t have speed therefore the kinetic energy is lower than potential energy and almost zero. However, at the bottom the kinetic energy is very high and equal to the total energy. That is because, when the skater is at B he is still in motion therefore he has more kinetic energy than potential energy. 4. Using the energy bar graph, does the simulation agree with your answers? Explain. The simulation has similar answers to mine. The kinetic energy is very high when at position B and almost equal to total energy. When at position TR and TL the kinetic energy is almost equal to zero and very low. 5. What does this simulation tell you about conservation of energy? Explain in detail what Conservation of energy means that the energy cannot be created or destroyed. Even though the various energies, such as the kinetic and potential energies in this case keep on changing (lowering and increasing) the total energy remains the same in every position. The type of energy transfers from one to other but they will always add up to the total energy which always remain the same in every case.

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6. If energy needs to be conserved, how can the kinetic energy of the skater change throughout his motion? Explain in detail! Conservation of energy doesn’t only depend on the presence of kinetic energy, there is also potential energy to account for. Therefore, even though the kinetic energy is changing the potential energy is working hand in hand with it to conserve the energy and maintain the total energy. For example, if the kinetic energy decreases the potential energy increases and adds up to the total energy and vice versa.

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PART D: With Friction Now in an environment with friction, some of the energy is converted (or some say “lost”) to thermal energy. Again, you will predict the Energy Bar Graphs, but this time with friction. The skater starts at TL and is released from rest. Predict what the Energy Bar Graph will look like. Different types of energy will change as the skateboarder begins moving and skates to B, then TR, then back to B, then back to TL. On the Energy Bar Graphs below, predict the amount of each type of energy at that point in the motion. If the skater does not reach TR or TL, then draw the Bar Graph for the highest point. One way to draw your predictions is to use the drawing tools in Word.

TL (start)

B

TR

B

5

TL

PART E: Check your predictions with the Energy Skate Park Basics Simulation Click on the Friction tab at the bottom. Select Bar Graph to display. Now simulate the motion with friction and check your graph predictions. In another color, fix your graphs. Do NOT erase your original predictions! 7. Explain what you observed that is different when friction is present. When Friction is present the skater slows down and eventually stops moving as he goes back and forth on the half-pipe. Also, there is thermal energy present now. Another thing I noticed about the bar graph is that thermal energy keeps on increasing whereas the potential and kinetic energy keep on decreasing overall.

8. Does thermal energy ever decrease? Why or why not? The thermal energy doesn’t decrease at all in this specific case, it keeps on increasing as the skater is released from the rest position till when the skater stops. The other energies are converting themselves to the thermal energies, therefore they are decreasing meanwhile the thermal energy is increasing to conserve energy.

9. What does this simulation tell you about conservation of energy? Explain in detail what conservation of energy means and how the simulation shows that energy is conserved. This stimulation again portrays that energy is conserved in every case even when friction is involved. This is noticeable because the total energy never changes. In this case the kinetic energy and potential energy decrease all together, therefore what will conserve the energy? That is when thermal energy comes in. It increases gradually and adds with potential and kinetic to conserve energy. The bar graph shows these changes in the types of energies and in a way compares it with the total energy, that is how the stimulation shows the energy is conserved.

10. The total of kinetic and potential energy is called mechanical energy. Is mechanical energy conserved in either of the two situations we have investigated? Explain. The mechanical energy is not conserved when friction is present, however it is conserved when friction is not present. Therefore, in the first part of the stimulation the mechanical energy was conserved (no friction), however in the friction part of the stimulation the mechanical energy is not conserved. That is because mechanical energy is not conserved when nonconservative forces are acting (friction). The kinetic and potential energy is lost as thermal energy (heat), reducing the mechanical energy.

11. Could the skate boarder do anything to increase his height on the half pipe? If he did, where would that energy come from? If you aren’t a skateboarder, then think about swinging on a swing. Can you go higher without anyone pushing you? How do you do that? There is a possibility for the skate boarder to increase his height on the half pipe by applying force using his body, and this energy would come from an outward source and increase the total energy of the system. While swinging o the swing we do the same thing, we use the thrust of our bodies to push ourselves higher, that is adding an external energy in to the system. 6

12. Would we need to include that new energy source in our calculation of total energy conservation? Yes, we need to include that new energy into our calculation of total energy conservation. That has to happen because that new energy is part of the system and would affect the other energies working on the system as well.

13. Repeat the experiment with different settings for the mass. Describe the similarities and differences you find. When the mass of the skateboarder increases so does the total energy, since the total energy increases the reaming energy (kinetic and potential) also are that high in the beginning but then slowly decline, while thermal increases. The increases and decrease of the energies occur in the same fashion if the mass is average like it was above. If the mass is smaller however the total energy is way smaller. 14. Repeat the experiment with different settings for the friction. Describe the similarities and differences you find. One noticeable difference when the friction is increased is that the skateboarder slows down faster compared to when the friction is less. The rate of energy being transferred to thermal from kinetic and potential is faster. Vice versa if the friction is reduced, if there is no friction then the stimulation would look similar to part B of stimulation. The similarities would be the total energies remain the same for all intensity of frictions and the way the energies decrease is same is just the rate that is different.

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PART F: Loop the Loop Click on the tab labeled Playground. Set the friction to none and click the option to allow the skater to fall off as shown on the right. Construct a skateboard ramp with multiple segments that will allow the skater to complete a loop without falling off. Write your observations about what must be done to make the track successful. What do you observe about the starting height? Also copy and paste your final skateboard park design below. For the track to be successful the starting height of the ramp should be set up at a very high position and the loop has to be below the starting position of the ramp. I had two loops included in my ramp. The starting position of the ramp was very high then the first loop was a little below that height and the second loop was a little below the first loop (height wise). It is necessary for the ramp to start from a high position because then the total energy increases and this energy is necessary for high kinetic energy which will allow for the skateboarder to complete the loop without falling.

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