krit.club logo

Energy - Renewable and Non-renewable Energy

Grade 6Cambridge (IGCSE)

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

•

Energy is the capacity to do work and is measured in the SI unit Joules (JJ).

•

Non-renewable energy resources are finite sources that cannot be replaced once consumed. Examples include fossil fuels (Coal, Oil, Natural Gas like CH4CH_4) and Nuclear fuels like Uranium (235U^{235}U).

•

Renewable energy resources are naturally replenished over short periods of time. Examples include Solar, Wind, Hydroelectric, Tidal, and Geothermal energy.

•

The Law of Conservation of Energy states that energy cannot be created or destroyed, only transformed from one form to another (Einput=EoutputE_{input} = E_{output}).

•

Fossil fuels release Greenhouse Gases, primarily Carbon Dioxide (CO2CO_2), which contribute to the enhanced greenhouse effect and global warming.

•

Energy stores include Kinetic Energy (KEKE), Gravitational Potential Energy (GPEGPE), Chemical Energy, and Thermal Energy (QQ).

📐Formulae

Efficiency=Useful Energy OutputTotal Energy Input×100%Efficiency = \frac{\text{Useful Energy Output}}{\text{Total Energy Input}} \times 100\%

GPE=m×g×hGPE = m \times g \times h

KE=12mv2KE = \frac{1}{2}mv^2

W=F×sW = F \times s

💡Examples

Problem 1:

A coal-fired power station consumes 2000 MJ2000\,MJ of chemical energy to produce 600 MJ600\,MJ of useful electrical energy. Calculate the efficiency of the power station.

Solution:

Efficiency=600 MJ2000 MJ×100=30%Efficiency = \frac{600\,MJ}{2000\,MJ} \times 100 = 30\%

Explanation:

Efficiency is calculated by dividing the useful energy output by the total energy input. Here, 1400 MJ1400\,MJ of energy is wasted as thermal energy (heat) and sound.

Problem 2:

An object with a mass (mm) of 10 kg10\,kg is lifted to a height (hh) of 5 m5\,m. Calculate the Gravitational Potential Energy gained, assuming gravity (gg) is 9.8 m/s29.8\,m/s^2.

Solution:

GPE=10 kg×9.8 m/s2×5 m=490 JGPE = 10\,kg \times 9.8\,m/s^2 \times 5\,m = 490\,J

Explanation:

Using the formula GPE=mghGPE = mgh, we multiply the mass, the acceleration due to gravity, and the vertical height to find the energy stored in the gravitational field.

Problem 3:

Identify the chemical reaction for the combustion of Methane, a common non-renewable energy source.

Solution:

CH4+2O2→CO2+2H2O+EnergyCH_4 + 2O_2 \rightarrow CO_2 + 2H_2O + \text{Energy}

Explanation:

Methane (CH4CH_4) reacts with Oxygen (O2O_2) to produce Carbon Dioxide (CO2CO_2) and Water (H2OH_2O), releasing thermal energy used to generate steam in power plants.