Cambridge IGSCE Physics - Chapter 4 Review

Joule

The SI Unit of work. 1J moves an object 1m when 1N of force is applied.

What is the formula for Work?

Work = Force * Parallel Distance

Energy

The amount of work that could be done. Joules in its storage form.

Kinetic Energy

Energy from motion. KE = ½ mv²

Gravitational Potential Energy

Energy from a object being lifted up. GPE = mgh

Elastic/Strain Energy

Energy from stretched or compressed objects.

Chemical Energy

Energy stored in atomic bonds.

Electrostatic Energy

Energy from attractive electrical charges that are held apart.

Nuclear Energy

Atoms’ particles are bounded by strong forces. If the particles become rearranged, or the nucleus splits, the stored forces are released.

In the Sun, nuclear energy is released via nuclear fusion (combining atoms).

Thermal Energy

Energy stored as the atoms vibrating in objects.

Magnetic Energy

Energy stored as the force trying to attract two magnets that are held apart.

What are the types of energy transfers?

• Mechanical (by motion)

• Electrical (by a current)

• Heating (heat moving from hot places to cooler places)

• Radiation (as light waves, sound waves)

Law of Conservation of Energy

Energy can be stored, transferred, or dissapated but not created or destroyed.

Formula for Calculating Effeciency

Efficiency = useful energy or power output / total energy or power input

Watt

The measurement of power.

Power

The rate at which work is done. Power = work done or energy transferred / time taken

Describe how Thermal Power Stations operate

Fuel (Coal, Oil, Natural Gas) is burned into thermal energy used to heat a boiler. The boiler creates steam which spins turbines. This rotational energy is then used to power a generator producing electricity.

Nuclear Reactor

A place where nuclear fission occurs, releasing thermal energy.

District Heating:

Whenever thermal energy is wasted from power stations, it can be used to heat water pipes to heat residential areas.

What is the issue with Thermal Power Stations?

• Burning coal releases Co2 and Sulfur into the atmosphere.

• Transporting fuel can lead to oil leaks.

• Radioactive Waste is very dangerous.

• Nuclear Accidents are devastating.

Non-Polluting Power Stations

Hydroelectric, Tidal, Pumped Water Storage, and Wind Generators.

Renewable Energy Sources

• Hydroelectric

• Tidal

• Wind

• Wave (difficult to engineer)

• Geothermal (deep drilling is difficult/expensive)

• Solar (expensive, inefficient, sunlight is variable)

• Biofuels (a large amount of land is needed to supply plants)

Non-Renewable Energy Sources

• Fossil Fuels (Oil, Coal, Natural Gas)

  pros: natural gas is methane, which is not that polluting.

  cons: releases harmful gases.

• Nuclear Energy (Uranium)

  pros: extremely efficient.

  cons: dangerous, hard to build and maintain nuclear reactors.

• Shale Gas (found in shale by fracking).

  pros: future source of gas

  cons: environmental concerns.