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 (B)

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

In a closed system, energy can leave the system.

<p>False (B)</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 (B)</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 (B)</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 (D)</p> Signup and view all the answers

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

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

Electric heaters are generally considered 100% efficient.

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

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

<p>False (B)</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 (C)</p> Signup and view all the answers

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

<p>False (B)</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 (C)</p> Signup and view all the answers

Solar cells can generate electricity during the night.

<p>False (B)</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 (D)</p> Signup and view all the answers

Renewable energy resources will eventually be depleted.

<p>False (B)</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 (D)</p> Signup and view all the answers

Biofuels are considered renewable energy resources.

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

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

<p>True (A)</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 (A)</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 (A)</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

Flashcards

Definition of Conduction

Energy transfer between particles by vibration.

What is Thermal Conductivity?

Material's ability to transfer heat quickly.

How does Convection work?

Heating causes particles to move and rise, creating a current.

Convection Happens in?

Liquids and Gases

Signup and view all the flashcards

Convection Example

Radiators create convection currents in rooms.

Signup and view all the flashcards

Specific Heat Capacity

The amount of energy needed to increase the temperature of 1 kilogram of a substance by 1°C.

Signup and view all the flashcards

Conservation of Energy Principle

Energy cannot be created or destroyed, only transferred or changed from one form to another.

Signup and view all the flashcards

Energy Transfer

Energy moving from one object or place to another.

Signup and view all the flashcards

Equation for specific heat capacity

ΔE = mcΔθ, where ΔE is the change in thermal energy, m is the mass, c is the specific heat capacity, and Δθ is the temperature change.

Signup and view all the flashcards

Investigating specific heat capacity of solids

A method for finding the specific heat capacity of a solid material. The process involves heating the material and monitoring the temperature change over time

Signup and view all the flashcards

Dissipated Energy

Energy lost to a less useful form of energy, often heat.

Signup and view all the flashcards

Power

The rate at which energy is transferred or work is done.

Signup and view all the flashcards

Investigating specific heat capacity of liquids

A method for finding the specific heat capacity of a liquid material using either an insulated container and monitoring the temperature change.

Signup and view all the flashcards

Unit of Power

Watt (W)

Signup and view all the flashcards

Calculating energy transferred

E = Pt (Energy = power x time), Use this when you know the power of the heating source, and how long it was operating

Signup and view all the flashcards

Powerful Machine

Machine transferring significant energy quickly.

Signup and view all the flashcards

Graph of energy vs. temperature

A graph plotting energy transferred against the temperature of a substance. The gradient of the straight-line section relates to the specific heat capacity.

Signup and view all the flashcards

Power Calculation

Power = Energy/Time or Power = Work/Time

Signup and view all the flashcards

Specific heat capacity of water

4200 J/kg°C

Signup and view all the flashcards

Closed System (Energy)

A system where no energy enters or leaves.

Signup and view all the flashcards

Units of specific heat capacity

J/kg°C

Signup and view all the flashcards

Efficiency

A measure of how well a device converts input energy into useful output energy. It is a ratio of useful output energy to total input energy.

Signup and view all the flashcards

Wasted Energy

Energy that is lost during a transfer, often transferred into thermal energy stores.

Signup and view all the flashcards

Calculating Efficiency

Efficiency can be calculated by dividing the useful energy output by the total input energy, or by dividing the useful power output by the total power input.

Signup and view all the flashcards

Electric Heater Efficiency

Electric heaters are usually 100% efficient, meaning all electrical energy is converted to heat.

Signup and view all the flashcards

Why is 100% Efficiency Impossible?

In real-world devices, some energy will always be lost as heat during energy transfers, making 100% efficiency unattainable.

Signup and view all the flashcards

Lubrication's Role

Lubricants, like oil, reduce friction between moving surfaces, decreasing energy loss due to friction.

Signup and view all the flashcards

Friction's Effect

Friction converts kinetic energy (movement) into thermal energy (heat), causing energy dissipation.

Signup and view all the flashcards

Insulation's Goal

Insulation aims to minimize energy (heat) loss from a building, improving its efficiency.

Signup and view all the flashcards

Cavity Wall Insulation

A layer of air inside the walls reduces heat transfer by conduction, slowing energy loss from the house.

Signup and view all the flashcards

Loft Insulation

Insulation in the attic reduces convection currents, preventing warm air from escaping.

Signup and view all the flashcards

Double-Glazed Windows

The air trapped between panes of glass reduces heat transfer by conduction, keeping heat inside.

Signup and view all the flashcards

Draught Excluders' Role

These seal gaps around doors and windows, minimizing heat loss due to convection.

Signup and view all the flashcards

Investigating Insulation

Comparing temperature changes in a container with different insulation materials helps determine their effectiveness.

Signup and view all the flashcards

Wind Power

Generating electricity using wind turbines that rotate blades connected to generators.

Signup and view all the flashcards

Solar Cell Energy

Generating electricity directly from sunlight using solar cells.

Signup and view all the flashcards

Geothermal Energy

Harnessing heat from Earth's interior, often found near volcanic areas or hot rocks, to generate electricity.

Signup and view all the flashcards

Pros of Renewable Energy

Renewable energy sources, like wind, solar, and geothermal, offer advantages such as being pollution-free, reliable in certain conditions, and generally have low running costs.

Signup and view all the flashcards

Cons of Renewable Energy

Renewable energy sources have drawbacks such as high initial costs, dependence on weather conditions (wind, sun), and limited geographical suitability (geothermal).

Signup and view all the flashcards

Non-renewable energy

Energy sources that are finite and will eventually run out. They formed over millions of years and are typically burned to produce energy.

Signup and view all the flashcards

Fossil fuels

Non-renewable energy sources like coal, oil, and natural gas, formed from the remains of ancient organisms.

Signup and view all the flashcards

Renewable energy

Energy sources that are constantly replenished by natural processes and will never run out.

Signup and view all the flashcards

Solar energy

Renewable energy derived from the sun's radiation, often used for electricity generation or water heating.

Signup and view all the flashcards

Bio-fuel

Renewable energy source made from recently living organisms, often from crops or agricultural waste.

Signup and view all the flashcards

Energy in Transportation

Using energy resources to power vehicles, including non-renewable options like petrol and diesel, and renewable options like bio-fuels and electric vehicles.

Signup and view all the flashcards

Energy in Heating

Using energy resources to heat buildings and water, with options ranging from non-renewable natural gas and coal to renewable geothermal and solar energy.

Signup and view all the flashcards

Distinguishing Renewable and Non-renewable

Identifying whether an energy source is constantly replenished (renewable) or finite (non-renewable), considering factors like the rate of depletion and the resources required.

Signup and view all the flashcards

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser