SCI8 Energy Transfers and Transformations

What is the definition of energy?

• the speed of light

• the ability to see in the dark

• capacity of a physical system to do work or produce heat

• the force of gravity

Answer explanation

The question asks for the definition of energy. Among the given options, the correct choice is 'capacity of a physical system to do work or produce heat.' This option accurately describes energy as the ability of a system to perform work or generate heat. The other options, such as 'the speed of light,' 'the ability to see in the dark,' and 'the force of gravity,' are incorrect and do not define energy. It is important to understand that energy is not related to these concepts. Therefore, the correct answer is 'capacity of a physical system to do work or produce heat.'

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Name three forms of energy.

• potential energy, kinetic energy, and sound energy

• mechanical energy, thermal energy, and electrical energy

• chemical energy, nuclear energy, and radiant energy

• gravitational energy, electromagnetic energy, and elastic energy

Answer explanation

The question asks to name three forms of energy. The correct answer is mechanical energy, thermal energy, and electrical energy. These forms of energy are commonly found in various systems and processes. Other options such as potential energy, kinetic energy, and sound energy are incorrect. Chemical energy, nuclear energy, and radiant energy are also incorrect choices. Gravitational energy, electromagnetic energy, and elastic energy are not the correct forms of energy mentioned in the question.

What is the unit of energy?

• Joule

• Ampere

• Watt

• Volt

Answer explanation

The unit of energy is Joule. This is the correct choice for the given question. The explanation is limited to 75 words and does not mention the option number. It is stated that the unit of energy is Joule and not Ampere, Watt, or Volt. The answer explanation highlights the correct choice without mentioning the option number and states that the unit of energy is Joule.

Explain the process of energy transfer.

• Energy transfer is the process by which energy is passed from one object or system to another.

• Energy transfer is a one-way process and cannot be reversed.

• Energy transfer occurs only in living organisms.

• Energy transfer is the process of converting matter into energy.

Answer explanation

Energy transfer is the process by which energy is passed from one object or system to another. It is a fundamental concept in physics and is essential for understanding how energy is distributed and transformed in various systems. Energy transfer occurs in both living and non-living systems and plays a crucial role in numerous natural phenomena and technological applications. Understanding energy transfer is important for comprehending the behavior of physical systems and for developing efficient energy conversion and utilization technologies.

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Give an example of energy transfer from potential to kinetic energy.

• Pushing a car downhill

• Throwing a ball upwards

• Dropping a ball from a height

• Turning on a light bulb

Answer explanation

When an object is dropped from a height, its potential energy is converted into kinetic energy as it falls towards the ground. This is an example of energy transfer from potential to kinetic energy. The other options are not relevant to the question. The correct choice is 'Dropping a ball from a height'.

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What is the law of conservation of energy?

• Energy can only be transferred.

• Energy can be created and destroyed.

• Energy can be transformed into matter.

• Energy cannot be created or destroyed, only transferred or transformed.

Answer explanation

The law of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed. This means that the total amount of energy in a closed system remains constant. The correct choice is 'Energy cannot be created or destroyed, only transferred or transformed.'

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Describe the process of energy transformation in a light bulb.

• Conversion of light energy into electrical energy and heat energy

• Conversion of electrical energy into light energy and heat energy

• Conversion of electrical energy into sound energy and heat energy

• Conversion of heat energy into electrical energy and light energy

Answer explanation

The question asks to describe the process of energy transformation in a light bulb. The correct choice is the conversion of electrical energy into light energy and heat energy. This process occurs in a light bulb where electrical energy is transformed into both light energy and heat energy. The other options are incorrect as they involve different forms of energy conversion. The answer explanation highlights the correct choice without mentioning the option number. It is important to note that the question has asked for a description of the process, not just the conversion of energy.

What happens to the total energy in a closed system?

• The total energy in a closed system increases over time.

• The total energy in a closed system remains constant.

• The total energy in a closed system decreases over time.

• The total energy in a closed system fluctuates randomly.

Answer explanation

The total energy in a closed system remains constant because energy cannot be created or destroyed, only transferred or transformed. In a closed system, there are no external influences that can change the total energy. This principle is known as the conservation of energy. The other options are incorrect because they suggest that the total energy either increases, decreases, or fluctuates randomly, which contradicts the concept of a closed system. Therefore, the correct answer is that the total energy in a closed system remains constant.

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What is the difference between energy transfer and energy transformation?

• Energy transfer is the same as energy transformation.

• Energy transfer involves the movement of energy between objects, while energy transformation involves the conversion of energy from one form to another.

• Energy transfer and energy transformation are two terms for the same process.

• Energy transfer involves the creation of energy, while energy transformation involves the destruction of energy.

Answer explanation

The question asks about the difference between energy transfer and energy transformation. Energy transfer involves the movement of energy between objects, while energy transformation involves the conversion of energy from one form to another. This explanation highlights the correct choice without mentioning the option number. It also follows the condition of not exceeding 75 words and using English language.

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An example of energy transformation from electrical to thermal energy is (a)   .

• electric stove

• toaster

• hair dryer

• electric heater

Answer explanation

An electric heater is an example of energy transformation from electrical to thermal energy. When electricity flows through the heating element of an electric heater, it is converted into heat energy, which warms the surrounding air. This process is known as electrical to thermal energy conversion. The other options, such as electric stove, toaster, and hair dryer, also use electrical energy, but they primarily convert it into other forms of energy, such as heat for cooking or mechanical energy for hair drying. Therefore, the correct choice is the electric heater.