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🔋college physics i – introduction review

Flywheel

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

A flywheel is a mechanical device designed to efficiently store rotational energy. It is a crucial component in the study of kinematics of rotational motion, as it helps maintain and regulate the angular velocity of a rotating system.

5 Must Know Facts For Your Next Test

  1. Flywheels store energy in the form of rotational kinetic energy, which can be released when needed to maintain or change the angular velocity of a system.
  2. The amount of energy a flywheel can store is directly proportional to its moment of inertia and the square of its angular velocity, as described by the formula for rotational kinetic energy.
  3. Flywheels are commonly used in mechanical systems to smooth out fluctuations in rotational speed, such as in engines, power tools, and other machinery.
  4. The design of a flywheel, including its size, shape, and material composition, can be optimized to maximize its energy storage capacity and efficiency.
  5. Flywheels can be used as a form of energy storage, allowing excess energy to be stored during periods of low demand and released when needed, making them a valuable component in renewable energy systems.

Review Questions

  • Explain how the moment of inertia of a flywheel affects its ability to store rotational energy.
    • The moment of inertia of a flywheel is a measure of its resistance to changes in rotational motion. A flywheel with a higher moment of inertia can store more rotational kinetic energy, as the formula for rotational kinetic energy shows that it is directly proportional to the moment of inertia. This means that a flywheel with a larger mass distribution around its axis of rotation will be able to store more energy, which can then be released to maintain or change the angular velocity of the system.
  • Describe how flywheels are used to smooth out fluctuations in rotational speed in mechanical systems.
    • Flywheels are often used in mechanical systems to help regulate and maintain a constant angular velocity, even in the face of fluctuations in the driving force or load. When the system experiences a temporary increase in angular velocity, the flywheel stores the excess rotational kinetic energy. Conversely, when the system experiences a decrease in angular velocity, the flywheel releases some of its stored energy to maintain the desired rotational speed. This smoothing effect helps to ensure consistent and efficient operation of the mechanical system, which is crucial in applications such as engines, power tools, and other machinery.
  • Analyze the potential role of flywheels in renewable energy storage systems and discuss the advantages they may offer compared to other energy storage technologies.
    • Flywheels have the potential to play a significant role in renewable energy storage systems, as they can efficiently store excess energy generated during periods of high production and release it when demand increases. Compared to other energy storage technologies, such as batteries, flywheels offer several advantages: they have a longer lifespan, can withstand a greater number of charge-discharge cycles, and are less affected by environmental factors like temperature. Additionally, flywheels can be quickly charged and discharged, making them well-suited for applications that require rapid energy storage and retrieval. This makes them a valuable component in renewable energy systems, where the intermittent nature of sources like wind and solar power requires efficient and flexible energy storage solutions to ensure a stable and reliable supply of electricity.