CH 4: Conservation of Energy
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Questions and Answers

What happens to the system's mechanical energy when non-conservative forces, like friction, are involved?

  • It always increases
  • It always decreases
  • It remains constant
  • It can increase or decrease (correct)
  • In the context of sliding objects, what is the primary form of energy that the initial kinetic energy gets converted into?

  • Thermal energy (correct)
  • Chemical energy
  • Elastic energy
  • Potential energy
  • When an object slides up an incline, which forces do work on it?

  • Only frictional forces
  • Only gravitational forces
  • Magnetic and electrical forces
  • Gravitational and frictional forces (correct)
  • What is the equation that describes energy conservation in the absence of non-conservative forces?

    <p>$ riangle E_k + riangle E_p = 0$</p> Signup and view all the answers

    Why is it essential to understand the distinction between conservative and non-conservative forces in real-world applications?

    <p>To predict and analyze physical situations effectively</p> Signup and view all the answers

    What does the conservation of energy principle state?

    <p>Energy can only be transformed from one form to another in an isolated system</p> Signup and view all the answers

    Which forces have associated potential energies and contribute to the conservation of mechanical energy in an isolated system?

    <p>Electrostatic forces</p> Signup and view all the answers

    What type of forces lead to a change in mechanical energy of the system?

    <p>Frictional forces</p> Signup and view all the answers

    In systems where only conservative forces are acting, what happens to the total mechanical energy?

    <p>It remains constant</p> Signup and view all the answers

    Which type of forces depends on the path taken for the work done?

    <p>Frictional forces</p> Signup and view all the answers

    If a ball is thrown vertically upward, which of the following forces is considered conservative?

    <p>Gravitational force acting on the ball</p> Signup and view all the answers

    In an isolated system with only conservative forces acting, which of the following quantities is conserved?

    <p>Total mechanical energy</p> Signup and view all the answers

    If a block slides across a rough surface, which form of energy is the initial kinetic energy primarily converted into?

    <p>Thermal energy</p> Signup and view all the answers

    In a system with both conservative and non-conservative forces acting, which of the following statements is true?

    <p>The total energy is always conserved</p> Signup and view all the answers

    Which of the following statements is true about the work done by a conservative force?

    <p>It is path-independent and depends only on initial and final positions</p> Signup and view all the answers

    If a pendulum is released from its initial position, which of the following types of energy transformations occur during its motion?

    <p>Kinetic energy is converted to potential energy, and vice versa</p> Signup and view all the answers

    Which of the following forces is responsible for the dissipation of mechanical energy in a real-world system?

    <p>Friction force</p> Signup and view all the answers

    In a closed system with only conservative forces acting, what can be said about the total energy of the system?

    <p>It remains constant</p> Signup and view all the answers

    Which of the following is an example of a non-conservative force?

    <p>Air resistance acting on a falling object</p> Signup and view all the answers

    In a system with only conservative forces acting, if the potential energy of an object increases, what happens to its kinetic energy?

    <p>The kinetic energy decreases</p> Signup and view all the answers

    Which of the following is NOT an example of a situation where non-conservative forces play a role?

    <p>A pendulum swinging in a vacuum</p> Signup and view all the answers

    If an object slides up an incline, which of the following equations correctly represents the change in mechanical energy?

    <p>$W_{nc} = \Delta E_k + \Delta E_p$</p> Signup and view all the answers

    If a sliding object comes to a stop due to friction, what happens to its initial kinetic energy?

    <p>It is primarily converted into thermal energy</p> Signup and view all the answers

    In the absence of non-conservative forces, what happens to the sum of the changes in kinetic and potential energy?

    <p>$\Delta E_k + \Delta E_p = 0$</p> Signup and view all the answers

    Which of the following statements is true about non-conservative forces?

    <p>They are path-dependent and do not have associated potential energies</p> Signup and view all the answers

    In a system where only conservative forces are acting, what happens to the total mechanical energy?

    <p>It is always conserved</p> Signup and view all the answers

    Which of the following is NOT a practical application where understanding the distinction between conservative and non-conservative forces is essential?

    <p>Perpetual motion machine design</p> Signup and view all the answers

    If a skier ascends a slope with friction, what happens to their mechanical energy?

    <p>It decreases</p> Signup and view all the answers

    Which of the following statements about energy conservation is true?

    <p>It applies to both systems with and without non-conservative forces</p> Signup and view all the answers

    In a situation where an object slides on a rough surface, what can be said about the work done by friction?

    <p>It decreases the object's mechanical energy</p> Signup and view all the answers

    In a system where both conservative and non-conservative forces are acting, which equation correctly represents the relationship between the work done by non-conservative forces (Wnc), the change in kinetic energy (ΔEk), and the change in potential energy (ΔEp)?

    <p>$W_{nc} = \Delta E_k + \Delta E_p$</p> Signup and view all the answers

    In the context of a skier ascending a slope with friction, which statement accurately describes the change in the skier's mechanical energy?

    <p>The mechanical energy decreases due to the work done against friction.</p> Signup and view all the answers

    If an object is sliding on a rough surface, and its initial kinetic energy is converted primarily into thermal energy due to friction, which principle is being illustrated?

    <p>Conservation of energy</p> Signup and view all the answers

    In a closed system with only conservative forces acting, which of the following statements is true regarding the total mechanical energy of the system?

    <p>The total mechanical energy remains constant.</p> Signup and view all the answers

    If a pendulum is released from its initial position, and air resistance is negligible, which of the following energy transformations occur during its motion?

    <p>Potential energy is converted into kinetic energy, and vice versa.</p> Signup and view all the answers

    In a real-world application involving a bullet penetrating a material, which of the following statements is true regarding the energy transformations that occur?

    <p>Both conservative and non-conservative forces are involved, and the total mechanical energy decreases.</p> Signup and view all the answers

    If an object slides down an inclined plane with negligible friction, which of the following statements accurately describes the energy transformations that occur?

    <p>Potential energy is converted into kinetic energy, with no energy loss.</p> Signup and view all the answers

    In a system where both conservative and non-conservative forces are acting, which of the following statements is true regarding the total energy of the system?

    <p>The total energy of the system may increase or decrease, depending on the relative magnitudes of the forces.</p> Signup and view all the answers

    If a block slides across a rough surface and comes to a stop due to friction, which of the following statements accurately describes the outcome?

    <p>The block's initial kinetic energy is converted into thermal energy.</p> Signup and view all the answers

    In a situation where an object is dropped from a height and experiences air resistance, which of the following statements accurately describes the energy transformations that occur?

    <p>Potential energy is converted into kinetic energy, and kinetic energy is dissipated due to air resistance.</p> Signup and view all the answers

    In a system where both conservative and non-conservative forces are present, which of the following statements is true regarding the total mechanical energy?

    <p>The total mechanical energy may decrease due to the presence of non-conservative forces.</p> Signup and view all the answers

    In a closed system with only conservative forces acting, which of the following statements accurately describes the relationship between potential energy and kinetic energy?

    <p>As potential energy decreases, kinetic energy must increase by an equal amount.</p> Signup and view all the answers

    Which of the following expressions represents the principle of conservation of energy in the absence of non-conservative forces?

    <p>$U_i + K_i = U_f + K_f$</p> Signup and view all the answers

    If a pendulum is released from its initial position, which of the following energy transformations occurs during its motion in the absence of non-conservative forces?

    <p>Potential energy is continuously converted to kinetic energy and vice versa.</p> Signup and view all the answers

    In a scenario where an object slides across a rough surface, which of the following statements accurately describes the transformation of energy?

    <p>The initial kinetic energy is converted into a combination of heat energy and potential energy.</p> Signup and view all the answers

    Which of the following statements accurately describes the work done by a conservative force?

    <p>The work done by a conservative force depends solely on the initial and final positions of the object.</p> Signup and view all the answers

    In a system where both conservative and non-conservative forces are present, which of the following statements is true regarding the total energy of the system?

    <p>The total energy of the system can increase or decrease, depending on the work done by the non-conservative forces.</p> Signup and view all the answers

    Which of the following statements accurately describes the relationship between the work done by a non-conservative force and the change in mechanical energy of a system?

    <p>The work done by a non-conservative force is not necessarily equal to the change in mechanical energy of the system.</p> Signup and view all the answers

    In a system where both conservative and non-conservative forces are acting, which of the following statements accurately describes the conservation of energy principle?

    <p>The total energy of the system, including all forms of energy, is always conserved.</p> Signup and view all the answers

    What happens to the initial kinetic energy of a sliding object influenced by friction?

    <p>It is primarily converted into thermal energy due to friction.</p> Signup and view all the answers

    When an object slides up an incline, which forces do work on it?

    <p>Both gravitational (a conservative force) and frictional (a non-conservative force) forces.</p> Signup and view all the answers

    In a system with only conservative forces acting, what can be said about the total mechanical energy?

    <p>It remains constant.</p> Signup and view all the answers

    What is the outcome regarding mechanical energy when non-conservative forces like friction are involved?

    <p>The mechanical energy can either increase or decrease.</p> Signup and view all the answers

    Why is understanding the distinction between conservative and non-conservative forces important in real-world applications?

    <p>It allows for accurate prediction and analysis of physical outcomes.</p> Signup and view all the answers

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