Work, Energy & Power Concepts
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Questions and Answers

What is the definition of work in physics?

  • Work is defined as the product of force and distance in the direction of the force. (correct)
  • Work is defined as the total energy of an object.
  • Work is defined as the rate of energy transfer.
  • Work is defined as the change in kinetic energy.

    • Which of the following units is NOT equivalent to work?

  • Foot-pound
  • Watt (correct)
  • Joule
  • Newton metre

    • If a force of 20N moves an object through 15m, how much work is done?

  • 300 J (correct)
  • 400 J
  • 50 J
  • 150 J

    • What is the formula to calculate work done when a force is applied at an angle?

    <p>Work = Fdcosθ (A)</p> Signup and view all the answers

    How is the work done against gravity calculated when lifting a mass?

    <p>Work = mgh (B)</p> Signup and view all the answers

    A boy runs up a staircase with 30 steps, where each step is 15cm high. If his mass is 80kg and g = 10 m/s², how much work is done by the boy?

    <p>3600 J (D)</p> Signup and view all the answers

    When lifting a mass of 12kg through a distance of 1.25m with a force of 35N, what is the work done?

    <p>43.75 J (D)</p> Signup and view all the answers

    What information is needed to calculate work when a force is applied at an angle?

    <p>The distance moved and angle of application. (D)</p> Signup and view all the answers

    What is the formula for calculating work done?

    <p>Work done = Force x distance (D)</p> Signup and view all the answers

    Which type of energy is stored in the nucleus of atoms?

    <p>Nuclear energy (C)</p> Signup and view all the answers

    What is the unit of measurement for energy?

    <p>Joules (A)</p> Signup and view all the answers

    How is potential energy calculated?

    <p>P.E = mass x gravity x height (B)</p> Signup and view all the answers

    If a body of mass 30 kg is lifted to a height of 5 m, what is its potential energy? (Use g = 10 m/s²)

    <p>1500 Joules (D)</p> Signup and view all the answers

    What type of energy is characterized by a body in motion?

    <p>Kinetic energy (D)</p> Signup and view all the answers

    What is the potential energy of an object with a mass of 0.55 kg at a height of 14.2 m? (Use g = 10 m/s²)

    <p>78.1 Joules (B)</p> Signup and view all the answers

    If an object has a potential energy of 55 Joules and a mass of 15 kg, what is its height? (Use g = 10 m/s²)

    <p>0.366 m (A)</p> Signup and view all the answers

    Flashcards

    Work

    Work is done when a force moves an object some distance in the direction of the force.

    Work Formula

    Work = Force x Distance

    Work Unit

    The SI unit of work is the joule (J).

    Force Calculation

    Force = mass x acceleration (F=ma)

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    Inclined Force Work

    Work done by a force at an angle = Fd cos θ

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    Lifting Work Formula

    Work = mgh (lifting)

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    Work Calculation Example

    Calculating work done, for example, includes using the formula by plugging in the known values for force and distance.

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    Calculating work against gravity

    Work done against gravity is weight multiplied by the height.

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    Potential Energy

    Potential energy is the stored energy an object has due to its position or state. It's the energy an object has the potential to use.

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    Potential Energy Formula

    Potential energy (PE) is calculated by multiplying the object's mass (m), acceleration due to gravity (g), and its height (h): PE = mgh

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    Kinetic Energy

    Kinetic energy is the energy an object possesses due to its motion.

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    Kinetic Energy Calculation

    Kinetic energy (KE) is calculated by multiplying 1/2 the object's mass (m) and the square of its velocity (v): KE = 1/2mv²

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    Mechanical Energy

    Mechanical energy is the total energy of an object due to its motion and position. It's the sum of its potential energy and kinetic energy.

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    Forms of Energy

    Energy exists in different forms, including chemical, mechanical, nuclear, sound, hydro, and solar energy.

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    Study Notes

    Work, Energy & Power

    • Work: Work is done when a force moves an object through a distance. For work to occur, the force must be applied in the direction of the displacement.
    • Work Formula: Work = Force x Distance x cosθ, where θ is the angle between the force and the displacement
      • Work is measured in Joules (J) or Newton-meters (Nm).
      • Force is measured in Newtons (N).
      • Distance is measured in meters (m).
    • Force: Force = mass x acceleration (F = ma)
    • Example Calculation: A force of 20N moves an object 15m. The work done is 300 Joules (20 N x 15 m = 300 J).

    Different Forms of Energy

    • Energy: Energy is the ability to do work. It is measured in Joules.
    • Types of Energy:
      • Chemical Energy
      • Mechanical Energy (potential and kinetic)
      • Nuclear Energy
      • Sound Energy
      • Hydro Energy
      • Solar Energy

    Potential Energy

    • Potential Energy: Energy stored in an object due to its position or configuration.
    • Gravitational Potential Energy (GPE):
      • P.E. = mgh (mass x acceleration due to gravity x height)
      • Example Calculation: An 80kg boy climbs 4.5m. GPE = 3600 J (80 kg x 10 m/s² x 4.5 m = 3600 J).

    Kinetic Energy

    • Kinetic Energy: Energy an object possesses due to its motion (movement).
    • Kinetic Energy Formula: KE = 1/2mv² (one-half x mass x velocity²).
      • Mass (m) is in kilograms (kg).
      • Velocity (v) is in meters per second (m/s).
      • Kinetic energy (KE) is in Joules (J).
    • Example Calculation: A 25kg car moving at 15 m/s has kinetic energy of 2812.5 J (1/2 x 25 kg x (15 m/s)² = 2812.5 J).

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    Work, Energy & Power PDF

    Description

    Test your understanding of work, energy, and power with this quiz. Explore the definitions, formulas, and different forms of energy, including potential and kinetic energy. This quiz covers essential concepts necessary for mastering physics.

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