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Intro to Conservation of Energy quiz

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  • Which is the best example of the law of conservation of energy?
    The best example of the law of conservation of energy is a ball falling from a height in a vacuum, where its potential energy is converted to kinetic energy without any loss. This demonstrates that the total mechanical energy (sum of potential and kinetic energy) remains constant when only conservative forces, like gravity, are acting on the system.
  • What is the principle of conservation of mechanical energy?
    The principle states that the total mechanical energy (sum of kinetic and potential energy) of a system remains constant if only conservative forces are acting on it.
  • How do you calculate the initial mechanical energy of a falling ball?
    The initial mechanical energy is the sum of the initial kinetic energy and the initial potential energy, which can be expressed as 1/2 mvinitial^2 + mgyinitial.
  • What happens to the mechanical energy of a ball as it falls to the ground?
    The gravitational potential energy is converted into kinetic energy, but the total mechanical energy remains constant if no non-conservative forces are acting.
  • What is an isolated system in the context of energy conservation?
    An isolated system is one where no external forces are doing work, meaning only internal forces are acting within the system.
  • How does the choice of system boundaries affect energy conservation?
    The choice of system boundaries determines whether mechanical energy appears conserved, as including or excluding certain components (like a spring) affects the internal and external forces considered.
  • What distinguishes conservative forces from non-conservative forces?
    Conservative forces, like gravity and springs, allow mechanical energy to be conserved, while non-conservative forces, like friction, add or remove energy from the system.
  • What happens to mechanical energy when a block falls without air resistance?
    Mechanical energy is conserved as gravitational potential energy is converted to kinetic energy, with gravity being the only force acting.
  • How does friction affect the mechanical energy of a moving box?
    Friction removes energy from the system, converting kinetic energy into heat, thus reducing the total mechanical energy.
  • What is the effect of an applied force on a block at rest?
    An applied force increases the block's kinetic energy, adding energy to the system and making it non-conservative.