SCI8 Energy Transfers, Transformations & Waste Energy

What type of energy is stored in a wound-up spring in a toy car?

• Solar energy

• Kinetic energy

• Elastic potential energy

• Thermal energy

Answer explanation

The energy stored in a wound-up spring in a toy car is elastic potential energy. This type of energy is stored when an object is deformed, such as when a spring is compressed or stretched. When the spring is released, the stored energy is converted into kinetic energy, causing the toy car to move. Solar energy, thermal energy, and kinetic energy are not the correct types of energy stored in this situation.

When you turn on a torch (flashlight), what type of energy transformation is happening?

• Electrical energy

• Nuclear energy

• Sound energy

• Magnetic energy

Answer explanation

When you turn on a torch (flashlight), an energy transformation occurs. Electrical energy stored in the batteries is converted into light energy emitted by the bulb. This process involves the flow of electrons through the torch's circuit, which ultimately produces light. The correct choice is electrical energy, as it is the initial form of energy that gets transformed into light energy.

Why is it important to turn off the lights when you leave an empty room to save energy?

• To make the room darker

• To reduce waste energy

• To make it harder to find things

• To impress your friends

Answer explanation

Turning off the lights when leaving an empty room is important to save energy because it helps reduce waste energy. When lights are left on in an unoccupied room, they consume electricity unnecessarily, leading to higher energy bills and increased carbon emissions. By turning off the lights, you conserve energy and contribute to a more sustainable environment.

In an energy transformation experiment, when potential energy becomes kinetic energy, what does it mean?

• Energy is lost

• Energy is created

• Energy changes form

• Energy disappears

Answer explanation

The question is about the transformation of potential energy into kinetic energy. This process is an example of energy changing its form. It's not about energy being lost, created, or disappearing. Instead, it's about the energy already present in one form (potential) being converted into another form (kinetic). This is why 'Energy changes form' is the correct answer.

Using as little energy as possible to get a job done, like turning off the TV when you're not watching it, is called _____.

Answer explanation

The term for using as little energy as possible to get a job done, like turning off the TV when you're not watching it, is 'Energy efficiency'. This is because energy efficiency refers to using less energy to perform the same task - thus reducing energy waste. The other options, 'Energy greed' and 'Energy transformation', do not accurately describe this concept.

When a windmill turns wind energy into electrical energy, _____ energy is wasted in the process.

Answer explanation

When a windmill turns wind energy into electrical energy, some energy is inevitably wasted. This wasted energy is primarily in the form of sound energy. As the windmill's blades spin, they create noise, which is a form of sound energy. This energy does not contribute to the production of electrical energy, hence it is considered wasted.

If you leave the refrigerator door open, what happens to the cool air inside, and what type of energy is wasted?

• The air gets warmer

• Thermal energy is wasted

• The air disappears

• Sound energy is wasted

Answer explanation

When the refrigerator door is left open, the cool air inside mixes with the warmer air of the room, causing the temperature inside the refrigerator to rise. The refrigerator then has to work harder to cool down again, wasting thermal energy in the process. Therefore, the correct answer is 'Thermal energy is wasted'.

What happens to the total energy in a closed system according to the Law of Conservation of Energy?

• It decreases

• It increases

• It remains constant

• It multiplies

Answer explanation

The Law of Conservation of Energy states that energy cannot be created or destroyed, only transferred or transformed. Therefore, in a closed system, the total energy remains constant. It does not decrease, increase, or multiply. This principle is fundamental in physics and is the reason why 'It remains constant' is the correct answer to the question.

When you ride a bicycle, which energy transformation happens as you pedal and the bike moves forward?

• Elastic energy to light energy

• Chemical energy to kinetic energy

• Gravitational energy to sound energy

• Human energy to solar energy

Answer explanation

When you pedal a bicycle, your body uses chemical energy stored in the food you eat. This energy is converted into kinetic energy, which is the energy of motion that propels the bike forward. Therefore, the correct answer is 'Chemical energy to kinetic energy'.

What kind of energy is produced when you play music on a guitar, and the strings vibrate to make sound?

• Mechanical energy

• Magnetic energy

• Chemical energy

• Wind energy

Answer explanation

When you play music on a guitar, the strings vibrate to produce sound. This vibration is a form of mechanical energy, as it involves the movement of an object (the strings) due to a force. The other options, magnetic energy, chemical energy, and wind energy, are not directly involved in the production of sound from a guitar.