Understanding Energy Transfers and Sources

Which of the following is an example of kinetic energy?

• A compressed spring

• A moving car

• A charged battery

• A book on a shelf

Answer explanation

Kinetic energy is the energy of motion. A moving car is an example of kinetic energy because it is in motion, while the other options represent potential energy or stored energy.

What is the primary method of energy transfer in a vacuum?

• Conduction

• Convection

• Radiation

• Evaporation

Answer explanation

The primary method of energy transfer in a vacuum is radiation. Unlike conduction and convection, which require a medium, radiation can occur through empty space, allowing energy to travel as electromagnetic waves.

According to the law of conservation of energy, energy cannot be:

• Created or destroyed

• Transferred or transformed

• Measured or calculated

• Stored or released

Answer explanation

According to the law of conservation of energy, energy cannot be created or destroyed. This principle states that energy can only change forms or be transferred, but its total amount remains constant.

Which of the following is a renewable energy source?

• Coal

• Natural gas

• Solar power

• Nuclear power

Answer explanation

Solar power is a renewable energy source as it harnesses energy from the sun, which is abundant and sustainable. In contrast, coal, natural gas, and nuclear power are non-renewable or finite resources.

Which of the following is a non-renewable energy source?

• Wind energy

• Hydroelectric power

• Geothermal energy

• Oil

Answer explanation

Oil is a non-renewable energy source, meaning it cannot be replenished in a short time frame. In contrast, wind energy, hydroelectric power, and geothermal energy are renewable sources that can be naturally replenished.

What is the formula for calculating energy efficiency?

Answer explanation

The formula for calculating energy efficiency is \(\frac{\text{Useful energy output}}{\text{Total energy input}} \times 100\). This measures how effectively energy is converted into useful work.

Which of the following is a measure to improve energy efficiency in homes?

• Using incandescent light bulbs

• Installing double-glazed windows

• Leaving appliances on standby

• Using single-pane windows

Answer explanation

Installing double-glazed windows improves energy efficiency by providing better insulation than single-pane windows, reducing heat loss and energy consumption. In contrast, incandescent bulbs and leaving appliances on standby do not enhance efficiency.

What type of energy is stored in a stretched rubber band?

• Kinetic energy

• Thermal energy

• Elastic potential energy

• Chemical energy

Answer explanation

A stretched rubber band stores energy due to its deformation. This energy is called elastic potential energy, as it can be released when the band returns to its original shape.

Which method of energy transfer involves the movement of fluids?

• Conduction

• Convection

• Radiation

• Insulation

Answer explanation

Convection is the method of energy transfer that involves the movement of fluids, such as liquids and gases. It occurs when warmer fluid rises and cooler fluid sinks, creating a circulation pattern.

Which of the following is an advantage of using renewable energy sources?

• They are finite and will run out

• They produce greenhouse gases

• They are sustainable and reduce pollution

• They are more expensive to maintain

Answer explanation

The correct choice, 'They are sustainable and reduce pollution', highlights that renewable energy sources are not only abundant but also help in minimizing environmental impact, unlike fossil fuels.