How Do You Calculate the Kinetic Energy of a Flywheel?

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In summary, the question is asking for the kinetic energy of a flywheel that is rotated at a constant speed of 120rad/s by a 50W electric motor. The formula for kinetic energy is KE=(1/2)Iω^2, where I is the moment of inertia and ω is the angular speed. The student attempted to use the linear formula for kinetic energy, but was unsure of the mass and radius of the flywheel. They were also given information about linear velocity and power, but did not use it. The appropriate formula for this problem is KE=(1/2)Iω^2, which can be calculated using the given information.
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clairecho22
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Homework Statement


Q: A flywheel of moment of inertia 0.32kg/m^2 is rotated steadily at 120rad/s by a 50W electric motor. Find the kinetic energy of the flywheel.

Homework Equations


What is the best way to work this out? Am I using the right equations?
Can I simply substitute the angular rotation (120rad/s) instead of the velocity v in KE=(1/2)mv^2

The Attempt at a Solution


This is what I tried doing:
KE = (0.5).(m).(120)^2 but I still don't know the mass
Tried to use ω = v/r but I was not given the radius
To use power, I tried P = F.v -> P = m.a.v but I get stuck again because of mass and acceleration.Where: ω = angular speed; v = linear velocity; m = mass; P = Power; F = force; KE = Kinetic Energy; a = acceleration
 
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  • #2
The flywheel is only spinning, not translating. Use the appropriate formula.
 
  • #3
You've been given some information that you've not used.
Why do you think you were given it?

You've got the linear formula, the principle is the same for rotation. You just need to use the rotational analogues.
 

Related to How Do You Calculate the Kinetic Energy of a Flywheel?

1. What is a flywheel?

A flywheel is a mechanical device that stores rotational energy. It consists of a heavy wheel or disc that is mounted on a shaft and is used to store and release energy as needed.

2. Why is it important to find the KE of a flywheel?

Finding the kinetic energy (KE) of a flywheel is important because it allows us to understand the amount of energy that is stored in the flywheel. This information is crucial for designing and optimizing systems that use flywheels, such as engines and machines.

3. How do you calculate the KE of a flywheel?

The formula for calculating the KE of a flywheel is KE = 1/2 * I * ω^2, where I is the moment of inertia and ω is the angular velocity of the flywheel. The moment of inertia is a measure of an object's resistance to changes in its rotation, and the angular velocity is the rate at which the flywheel is rotating.

4. What factors affect the KE of a flywheel?

The KE of a flywheel is affected by several factors, including the mass and radius of the flywheel, the moment of inertia, and the angular velocity. Other factors that can impact the KE include friction, air resistance, and the materials used to make the flywheel.

5. How can the KE of a flywheel be used in practical applications?

The KE of a flywheel has many practical applications, such as in energy storage systems, hybrid vehicles, and mechanical devices. In these applications, the stored energy in the flywheel can be used to power other systems, making them more efficient and sustainable.

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