Physics Chapter on Energy Transfer and Power
47 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary mechanism of energy transfer in conduction?

  • Vibrating particles transferring energy to neighboring particles (correct)
  • Heat rising due to density differences
  • Movement of energetic particles
  • Energy flow through radiation

    • Convection can occur in solids.

    False

    What does thermal conductivity measure?

    How quickly energy is transferred through a material

    In convection, warmer regions of a fluid are __________ than cooler regions.

    <p>less dense</p> Signup and view all the answers

    Match the following terms with their correct descriptions:

    <p>Conduction = Transfer of energy through particle collisions Convection = Movement of particles from hot to cool regions Thermal conductivity = Speed of energy transfer in materials Convection current = Continuous movement of fluid due to temperature differences</p> Signup and view all the answers

    What does the conservation of energy principle state?

    <p>Energy can be transferred, stored, or dissipated but can never be created or destroyed.</p> Signup and view all the answers

    In a closed system, energy can leave the system.

    <p>False</p> Signup and view all the answers

    What unit is power measured in?

    <p>watts</p> Signup and view all the answers

    Power is defined as the rate of ______ transfer.

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

    If Motor A lifts an object in 50 seconds and Motor B in 300 seconds, which motor is more powerful?

    <p>Motor A</p> Signup and view all the answers

    Using the formula Power = Work done / Time, what is the power of Motor A if it lifts 8000 J of work in 50 s?

    <p>160 W</p> Signup and view all the answers

    Match the type of energy to its description:

    <p>Chemical energy = Stored in batteries Thermal energy = Heat energy Mechanical energy = Energy in moving objects Electrical energy = Energy from electric currents</p> Signup and view all the answers

    All energy transferred in a system is useful energy.

    <p>False</p> Signup and view all the answers

    What does the efficiency of a device measure?

    <p>The amount of useful energy output compared to input energy</p> Signup and view all the answers

    What is the main purpose of using lubricants in a system?

    <p>To reduce frictional forces</p> Signup and view all the answers

    Electric heaters are generally considered 100% efficient.

    <p>True</p> Signup and view all the answers

    Thicker walls with higher thermal conductivity will slow down energy transfer.

    <p>False</p> Signup and view all the answers

    What is the formula for calculating efficiency using energy transfer?

    <p>Efficiency = Useful output energy transfer / Total input energy transfer</p> Signup and view all the answers

    The efficiency of a device can be improved by __________ its surfaces.

    <p>insulating</p> Signup and view all the answers

    What is the effect of cavity wall insulation on energy transfer?

    <p>It reduces conduction through the walls by placing a layer of air between the inner and outer walls.</p> Signup and view all the answers

    Match the following devices with their described efficiencies:

    <p>Blender = 70% Electric heater = 100% Motor in remote-controlled car = Efficiency to be calculated Machine with useful power output of 900 W = Efficiency = 75%</p> Signup and view all the answers

    ___ energy is converted to thermal energy due to frictional forces.

    <p>Kinetic</p> Signup and view all the answers

    Match the following insulation methods with their benefits:

    <p>Cavity Walls = Reduces conduction Loft Insulation = Reduces convection currents Double-Glazed Windows = Air gaps reduce conduction Draught Excluders = Reduces convection around doors and windows</p> Signup and view all the answers

    Which of the following is NOT a method to improve thermal insulation?

    <p>Using oil as lubricant</p> Signup and view all the answers

    Materials like bubble wrap and cotton wool are poor thermal insulators.

    <p>False</p> Signup and view all the answers

    How does the thickness of an insulation layer affect temperature change?

    <p>Thicker insulation layers generally reduce the rate of temperature change.</p> Signup and view all the answers

    Which of the following is a disadvantage of wind power?

    <p>Can only produce energy when the wind is blowing</p> Signup and view all the answers

    Solar cells can generate electricity during the night.

    <p>False</p> Signup and view all the answers

    What is the primary energy source for geothermal power?

    <p>Decay of radioactive elements, mainly uranium</p> Signup and view all the answers

    Solar power is considered __________ after the initial investment.

    <p>free</p> Signup and view all the answers

    Match the energy source to its corresponding pro:

    <p>Wind Power = Minimal environmental damage Solar Cells = Low running costs Geothermal Power = Free energy</p> Signup and view all the answers

    Which of the following is a non-renewable energy resource?

    <p>Natural gas</p> Signup and view all the answers

    Renewable energy resources will eventually be depleted.

    <p>False</p> Signup and view all the answers

    Name one characteristic of non-renewable energy resources.

    <p>They will eventually be depleted.</p> Signup and view all the answers

    ______ energy resources can be used for heating buildings and include geothermal heat pumps.

    <p>Renewable</p> Signup and view all the answers

    Match the following energy resources with their type:

    <p>Solar = Renewable Coal = Non-renewable Wind = Renewable Nuclear fuel = Non-renewable</p> Signup and view all the answers

    What is the most common heating fuel in the UK?

    <p>Natural gas</p> Signup and view all the answers

    Biofuels are considered renewable energy resources.

    <p>True</p> Signup and view all the answers

    List two uses of energy resources in transport.

    <p>Fuel for vehicles, electricity for electric vehicles.</p> Signup and view all the answers

    What is the specific heat capacity of water?

    <p>4200 J/kg°C</p> Signup and view all the answers

    Materials that cool down rapidly have a low specific heat capacity.

    <p>True</p> Signup and view all the answers

    What is the equation used to calculate the change in thermal energy?

    <p>ΔE = mcΔθ</p> Signup and view all the answers

    To warm 1 kg of water by 1°C, _____ J of energy is needed.

    <p>4200</p> Signup and view all the answers

    Match the material with its specific heat capacity needed to heat 1 kg by 1°C:

    <p>Water = 4200 J/kg°C Mercury = 139 J/kg°C Copper = 385 J/kg°C Iron = 450 J/kg°C</p> Signup and view all the answers

    How much energy is required to heat 5 kg of water to increase its temperature by 1°C?

    <p>21000 J</p> Signup and view all the answers

    The gradient of the straight line in a graph of energy transferred vs. temperature represents the specific heat capacity.

    <p>True</p> Signup and view all the answers

    How can you determine the specific heat capacity of a solid material experimentally?

    <p>By measuring the energy supplied and the change in temperature using the equation c = 1/gradient x mass.</p> Signup and view all the answers

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser