Physics-Mechanical Energy
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Questions and Answers

What is the gravitational potential energy of a 0.5 kg book when it is 2 meters above a reference point?

  • 15 J
  • 20 J
  • 10 J (correct)
  • 5 J

    • How is mechanical energy defined in the context of physics?

  • The energy of an object due to motion only
  • The sum of kinetic energy and gravitational potential energy (correct)
  • The energy required to lift an object to a height
  • The total energy stored in an object

    • What does the equation ΔM.E = Wf−> M.Ef−M.E₁ = -f × d indicate?

  • The change in mechanical energy is dependent on displacement and friction force. (correct)
  • The initial mechanical energy is always greater than the final mechanical energy.
  • The relationship between work done and energy conservation.
  • The final mechanical energy can only be negative.

    • What would be the mechanical energy of a 0.1 kg bird flying at a speed of 10 m/s at a height of 50 m?

    <p>55 J</p> Signup and view all the answers

    If the height of the book is increased from 2 meters to 3 meters, what will be its new gravitational potential energy?

    <p>15 J</p> Signup and view all the answers

    Under what condition is mechanical energy conserved?

    <p>When friction or air resistance is neglected.</p> Signup and view all the answers

    What does the notation M.E₁ = M.Ef signify?

    <p>Initial mechanical energy is equal to final mechanical energy.</p> Signup and view all the answers

    Calculate the gravitational potential energy of the 0.5 kg book when it is 3 meters above the ground.

    <p>15 J</p> Signup and view all the answers

    How is energy lost due to friction expressed in terms of heat?

    <p>As q = |ΔM.E|, where ΔM.E is the change in mechanical energy.</p> Signup and view all the answers

    What condition determines that mechanical energy is not conserved?

    <p>Existence of friction or air resistance.</p> Signup and view all the answers

    What is the work done by the normal force when the displacement is perpendicular?

    <p>0 J</p> Signup and view all the answers

    How is the work done by friction calculated?

    <p>$W_f = -f \times d$</p> Signup and view all the answers

    If an object of mass 4 kg moves with a speed of 3 m/s, what is its kinetic energy?

    <p>12 J</p> Signup and view all the answers

    What is the work done by a force of 10 N over a distance of 10 m?

    <p>100 J</p> Signup and view all the answers

    How much work does a friction force doing 5 N over a distance of 10 m perform?

    <p>-50 J</p> Signup and view all the answers

    What is the kinetic energy of a 103 kg car moving at 20 m/s?

    <p>2 x 10^5 J</p> Signup and view all the answers

    How fast is a runner who covers 200 m in 40 seconds moving?

    <p>5 m/s</p> Signup and view all the answers

    What is the formula for gravitational potential energy?

    <p>G.P.E = m × g × h</p> Signup and view all the answers

    If an object has a mass of 50 kg at a height of 10 m, what is its gravitational potential energy?

    <p>5000 J</p> Signup and view all the answers

    Which unit is used to measure gravitational potential energy?

    <p>Joule (J)</p> Signup and view all the answers

    What is the formula for calculating the work done by a force along a displacement?

    <p>$W = F imes d$</p> Signup and view all the answers

    If a force of 50N is applied to move an object 4m in the direction of the force, how much work is done?

    <p>100J</p> Signup and view all the answers

    What is the necessary condition for calculating work done by a force?

    <p>The force must be constant and parallel to the displacement.</p> Signup and view all the answers

    What is the weight of an object if 600J of work is done in lifting it vertically by 3m?

    <p>200N</p> Signup and view all the answers

    In the context of work done, which scenario will result in zero work?

    <p>Lifting an object vertically with no displacement.</p> Signup and view all the answers

    Study Notes

    Mechanical Energy

    • Mechanical energy is either conserved or not conserved
    • If friction or air resistance is neglected, the principle of conservation of mechanical energy applies (mechanical energy is constant, M.Eᵢ = M.Ef)
    • If friction or air resistance exists, mechanical energy is not conserved (M.Eᵢ ≠ M.Ef). The change in mechanical energy (ΔM.E) equals the work done by friction (Wf), and the energy lost appears as heat (q = |ΔM.E|).

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    Description

    This quiz explores the principles of mechanical energy, focusing on conservation and non-conservation scenarios. It addresses the impact of friction and air resistance on mechanical energy, along with the relationship between work and energy loss. Test your understanding of how mechanical energy operates in various conditions.

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