Conservation of energy flywheel experiment

In summary, the conversation discusses an experiment involving different masses being dropped from a height and calculating their potential energy and the rotational velocity of a flywheel. The resulting graph shows the potential energy versus the square of the angular velocity, with the gradient being equal to 1/2I. The conversation also addresses the fact that the graph does not go through 0,0, which is explained by the fact that not all of the potential energy is converted to rotational energy in the flywheel. Suggestions for altering the experiment are also mentioned.
  • #1
jamie3009
4
0
Hi

Ive recently carried out an experiment where different masses are hung from a string and then dropped from the same height. The other end of the string is wrapped around the axle of a flywheel and when the mass hits the ground, the time for ten revolutions of the flywheel is calculated to give angular velocity. The potential energy of each of the masses is calculated using mgh and a graph of Ep vs ω2 is then plotted with the gradient = 1/2I. I am a bit stuck as to how to explain the graph and explain why the graph doesn't go through 0,0. My thoughts are that as the potential energy of the masses is increased, the kinetic energy of the flywheel also increases, as the angular velocity increases. I think the graph doesn't go through 0,0 to show that the flywheel still has some potential energy in the system when the kinetic energy is 0. Am i correct? Sorry for writing loads :)
 
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  • #2
Welcome to PF.

Ep is the potential energy of the mass and it is on the Y-axis, right? And the graph is crossing above 0 on the Y-axis? Then you are getting an output energy that is below your input energy. This would be because the weight hits the ground with kinetic energy: you aren't converting all of the potential energy to rotational energy in the flywheel.
 
  • #3
russ_watters said:
Welcome to PF.

Ep is the potential energy of the mass and it is on the Y-axis, right? And the graph is crossing above 0 on the Y-axis? Then you are getting an output energy that is below your input energy. This would be because the weight hits the ground with kinetic energy: you aren't converting all of the potential energy to rotational energy in the flywheel.

Thats correct. So does that mean that because the mass still has kinetic energy when it hits the floor, some is converted into sound etc and not all into rotational energy of the flywheel?
 
  • #4
jamie3009 said:
Thats correct. So does that mean that because the mass still has kinetic energy when it hits the floor, some is converted into sound etc and not all into rotational energy of the flywheel?
It's simpler than that. The change in potential energy of the falling mass increases both the kinetic energy of the flywheel and the falling mass. (They are connected by a string.) The energy used to increase the KE of the falling mass is energy not available to increase the KE of the flywheel. Doesn't matter what happens when the falling mass hits the ground.

See if you can derive the equation connecting the Δh of the falling mass with the resultant ω2.
 
  • #5
Another thing to do would be to alter the experiment. Replace your current axle with a conically shaped axle, that will release the weights at ~zero velocity immediately before they touch the ground. This eliminates the dropping mass kinetic energy variable.

cone.jpg

I'm sure there's a mathematical model for this, but my math skills are pretty much gone.
 

1. What is the Conservation of Energy Flywheel Experiment?

The Conservation of Energy Flywheel Experiment is an experiment that demonstrates the principle of conservation of energy, which states that energy cannot be created or destroyed, only transformed from one form to another. It involves using a flywheel, a rotating mechanical device, to observe how the energy input to the flywheel is conserved and transformed into other forms of energy such as kinetic and potential energy.

2. What materials are needed to conduct the Conservation of Energy Flywheel Experiment?

The materials needed for this experiment include a flywheel, a string, a pulley, a weight, a meter stick or ruler, and a stopwatch. The flywheel can be made from a bicycle wheel or any other circular object with a handle attached to it. The weight can be a small mass or a water bottle. The other materials can be easily found at home or purchased at a hardware store.

3. How is the Conservation of Energy demonstrated in this experiment?

The Conservation of Energy is demonstrated in this experiment by observing the energy input and output of the flywheel. The energy input is the work done by pulling the string to rotate the flywheel, while the energy output is the rotational kinetic energy of the flywheel. As the flywheel rotates, the kinetic energy increases, but the total energy remains constant, illustrating the principle of conservation of energy.

4. What are some potential sources of error in the Conservation of Energy Flywheel Experiment?

Some potential sources of error in this experiment include friction in the pulley and string, air resistance, and the accuracy of the timing. Friction in the pulley and string can cause the flywheel to slow down and decrease the measured rotational kinetic energy. Air resistance can also slow down the flywheel and affect the accuracy of the results. Additionally, accurate timing is crucial in this experiment to calculate the rotational kinetic energy, so any errors in timing can affect the results.

5. How can the results of the Conservation of Energy Flywheel Experiment be used in real-life applications?

The results of this experiment can be used to understand and demonstrate the principle of conservation of energy, which is a fundamental concept in physics. This principle has practical applications in various fields, such as engineering, where energy conservation is essential in designing efficient machines and systems. It also has implications in renewable energy sources, such as wind and hydroelectric power, where energy is converted and conserved in different forms. Finally, understanding the conservation of energy can help individuals make informed decisions about energy use and conservation in their daily lives.

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