Work, Power & Energy Resources (Edexcel IGCSE Physics)

In the gravitational potential energy equation, represents the mass of the object in kilograms (kg).

The equation for calculating gravitational potential energy is

Where:

• = change in gravitational potential energy

• = mass, measured in kilograms (kg)

• = gravitational field strength, measured in newtons per kilogram (N/kg)

• = height, measured in metres (m)

In the gravitational potential energy equation, represents the gravitational field strength in newtons per kilogram (N/kg).

False.

Energy is transferred away from an object's gravitational potential store when it falls.

Kinetic energy is the amount of energy an object has as a result of its mass and speed.

True.

Any object in motion possesses kinetic energy.

The equation for calculating kinetic energy is

Where:

• = kinetic energy, measured in joules (J)

• = mass, measured in kilograms (kg)

• = velocity, measured in metres per second (m/s)

False.

Kinetic energy is measured in units of joules (J).

In the kinetic energy equation, represents the speed of the object in meters per second (m/s).

In the kinetic energy equation, represents the mass of the object in kilograms (kg).

If an object has a mass of 2 kg and a velocity of 5 m/s, then it has 25 J of kinetic energy.

True.

Energy transfers can be assumed to be perfect (100% efficient) if the wasted energy is negligible.

True.

The energy transfers in a pendulum can be equated as .

This kind of energy equivalence is used in lots of calculations involving kinetic and gravitational potential energy.

Power is the rate at which energy is transferred or work is done, measured in watts (W).

False.

Power refers to the rate at which energy is transferred or work is done, not the total amount of energy transferred.

False.

A car has more power if it does the same amount of work in a shorter amount of time.

The formula for calculating power is:

Where:

• = power, measured in watts (W)

• = work done, measured in joules (J)

• = time, measured in seconds (s)

The rate of doing work, or power, refers to the amount of work done or energy transferred per unit time. It is measured in watts (W).

False.

Power is the rate at which energy is transferred or work is done, work done is the total amount of energy transferred.

False.

Power is typically measured in watts (W), while energy is measured in joules (J).

Solar cells, also known as photovoltaic cells, are devices made of semiconducting materials that produce electricity from sunlight.

True.

Solar energy is considered renewable because it is derived from the Sun which is expected to continue shining for billions of years.

Solar panels are devices that transfer energy from sunlight to the thermal store of the panels, which is then used to heat water.

The three main fossil fuels are:

• coal

• oil

• natural gas (methane)

Wave and tidal power stations generate electricity by utilising the motion of waves or tides to turn turbines, which then generate electricity through electromagnetic induction.

The main purpose of underwater turbines in wave and tide power systems is to transfer energy from the kinetic store of the moving water to the kinetic store of the turbines, which turn generators that generate electricity.

Hydroelectric dams are structures built across rivers to store water at a height in reservoirs. The water can be released, flowing over a turbine that turns a generator that generates electricity.

Geothermal energy is energy stored in the thermal store of rocks beneath the Earth's surface from tectonic heating. The hot rocks are used to heat water that can be used as a hot water supply and to produce steam to turn turbines for electricity generation.

False.

Geothermal energy is considered a renewable resource.

False.

Solar panels produce no greenhouse gases or pollution once they are operating.

False.

Burning fossil fuels produces carbon dioxide which is a greenhouse gas that contributes to global warming. But other harmful gases are also released in the combustion of fossil fuels, such as sulphur dioxide which causes acid rain.

Advantages of solar energy include:

• renewable

• reliable in hot climates

• produce no greenhouse gases or pollution

• Can be used in remote areas

The main advantage of hydroelectric dams is their ability to respond to electricity demand quickly and reliably.

The main advantages of biofuels are:

• renewable

• carbon neutral

True.

Nuclear power stations do not release pollution into the atmosphere during normal operation.

False.

Solar farms need to be large-scale to produce significant amounts of electricity.

The disadvantages of using fossil fuels include:

• non-renewable (so will run out)

• produce carbon dioxide which contributes to global warming

• produce sulphur dioxide which causes acid rain

The primary advantages of wave and tide power are that they are renewable energy resources that produce no pollution.

The main disadvantage of hydroelectric dams is that they require valleys to be flooded. This results in the destruction of habitats, towns, and villages.

The primary advantage of geothermal energy is its reliability and renewability. It offers a consistent source of heating and electricity production.

The main disadvantage of geothermal energy is the limited availability of suitable locations for large-scale electricity production.