Energy Stores and Transfers in Physics

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Questions and Answers

What does ΔE represent in the equation ΔE = mcΔT?

Change in thermal energy (correct)

Specific heat capacity

Change in temperature

Mass

Energy can be created or destroyed during a transformation.

False

What is the equation for calculating efficiency?

Efficiency = Useful energy output / Total energy input

The transfer of heat through solids occurs mainly through __________.

conduction Signup and view all the answers

Match the following energy resources with their characteristics:

Solar = Renewable and environmentally friendly Coal = Non-renewable and harmful to the environment Wind = Renewable and depends on weather conditions Natural Gas = Non-renewable and relatively inexpensive Signup and view all the answers

What is the main purpose of step-up transformers in the National Grid?

Increase voltage to reduce energy loss Signup and view all the answers

Convection occurs through solid materials.

False Signup and view all the answers

Define power in the context of energy transfer.

Power is the rate at which work is done or energy is transferred. Signup and view all the answers

Which energy store is associated with the energy of motion?

Kinetic energy Signup and view all the answers

Chemical energy is stored in the bonds of molecules and does not relate to fuels.

False Signup and view all the answers

What is the equation for calculating gravitational potential energy?

E = mgh Signup and view all the answers

The energy required to increase the temperature of 1 kilogram of a substance by 1 degree Celsius is called _____ capacity.

specific heat Signup and view all the answers

Which of the following is NOT one of the eight energy stores?

Mechanical Signup and view all the answers

What type of energy is stored within a compressed or stretched object?

Elastic potential energy Signup and view all the answers

Match the energy types with their definitions:

Kinetic = Energy of motion Thermal = Energy related to temperature Chemical = Energy stored in molecular bonds Nuclear = Energy stored in the atomic nucleus Signup and view all the answers

Energy is transferred by a force acting over a distance is referred to as _____ done.

work Signup and view all the answers

Study Notes

Energy Stores

There are eight different energy stores: kinetic, thermal, gravitational potential, elastic potential, chemical, electrostatic, magnetic, and nuclear.
Kinetic energy is the energy of motion; it is higher when an object moves faster and/or has more mass.
Thermal energy is the energy of a substance related to its temperature.
Gravitational potential energy is the energy an object has due to its position in a gravitational field.
Elastic potential energy is the energy stored within a stretched or compressed object.
Chemical energy is the energy stored in the bonds of molecules, for example, in fuels.
Electrostatic energy is the energy stored in a charged particle.
Magnetic energy is the energy stored in a magnetic field.
Nuclear energy is the energy stored in the nucleus of an atom.

Energy Transfers

Three main ways energy can be transferred between stores:
- Heating: Energy is transferred from a hotter object to a cooler object.
- Work Done: Energy is transferred by a force acting over a distance.
- Radiation: Energy is transferred via electromagnetic waves (e.g., light from the sun).
Example: A tennis ball dropped from a height.
- Initial state: Gravitational potential energy store.
- Falling: As the ball falls, its gravitational potential energy converts into kinetic energy, and the ball gains speed.
- Just before impact: Most of the energy is in the kinetic energy store.

Kinetic Energy

Equation: E = 1/2mv²
- E: Kinetic energy (measured in Joules, J)
- m: Mass (measured in kilograms, kg)
- v: Velocity (measured in meters per second, m/s)

Gravitational Potential Energy

Equation: E = mgh
- E: Gravitational potential energy (measured in Joules, J)
- m: Mass (measured in kilograms, kg)
- g: Gravitational field strength (measured in Newtons per kilogram, N/kg, or meters per second squared, m/s²)
- h: Height (measured in meters, m)

Elastic Potential Energy

Equation: E = 1/2kx²
- E: Elastic potential energy (measured in Joules, J)
- k: Spring constant (measured in Newtons per meter, N/m)
- x: Extension or compression (measured in meters, m)

Specific Heat Capacity

The energy required to increase the temperature of 1 kilogram of a substance by 1 degree Celsius.
Equation: ΔE = mcΔT
- ΔE: Change in thermal energy (measured in Joules, J)
- m: Mass (measured in kilograms, kg)
- c: Specific heat capacity (measured in Joules per kilogram per degree Celsius, J/kg°C)
- ΔT: Change in temperature (measured in degrees Celsius, °C)

Conservation of Energy

Energy cannot be created or destroyed, only transferred, stored, or dissipated.
Implication: The total amount of energy in the universe is constant.

Power

The rate at which work is done or energy is transferred.
Equation: Power = Work done / Time taken
- or Power = Energy transferred / Time taken
- Power (measured in Watts, W)
- Work done and Energy transferred (measured in Joules, J)
- Time taken (measured in seconds, s)

Conduction

Heat transfer through solids by vibration of particles.
Explanation: Hot particles vibrate faster, transferring energy to neighboring particles, causing them to vibrate faster as well.

Convection

Heat transfer through liquids and gases by movement of the fluid.
Explanation: Warmer, less dense fluids rise, and cooler, denser fluids sink, creating cycles that distribute heat.

Efficiency

The proportion of the total energy input that is converted into useful output energy.
Equation: Efficiency = Useful energy output / Total energy input
- Efficiency (usually expressed as a percentage)

Energy Resources

Renewable: Energy sources that are constantly replenished naturally (e.g., solar, wind, hydroelectric, tidal, geothermal, biomass).
- Pros: Renewable, less harmful to the environment.
- Cons: Can be unreliable, expensive to build.
Non-renewable: Energy sources that are finite and will eventually run out (e.g., fossil fuels (coal, oil, natural gas), nuclear).
- Pros: Reliable, relatively inexpensive.
- Cons: Will run out, harmful to the environment.

National Grid

A system of power lines and transformers that carry electricity across a country.
Purpose: Distribute electricity from power stations to homes and businesses efficiently.
- Step-up Transformers: Increase voltage to reduce energy loss during transmission.
- Pylons: Support high-voltage power lines.
- Step-down Transformers: Decrease voltage to safe levels for use in homes and businesses.

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Description

This quiz covers the eight different energy stores, including kinetic, thermal, and chemical energy. It also explores the methods of energy transfer, such as heating and work done. Test your knowledge of these fundamental concepts in physics!