Questions and Answers
What characteristic do all forms of energy share?
How much energy is used when lifting an apple 1 meter off the ground?
Which of the following is true regarding potential energy?
What is the formula for calculating kinetic energy?
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What unit is used to measure energy in batches of 1000 joules?
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What does energy efficiency refer to?
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Which equation represents gravitational potential energy?
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What is the relationship between kilocalories and kilojoules?
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Study Notes
Overview of Energy
- Energy exists in everything and is fundamental to the universe.
- Defined as the ability to perform work or induce change.
Measurement of Energy
- Energy is measured in Joules (J); 1 joule is used to lift an apple 1 meter.
- Energy is typically recorded in larger units like kilojoules (kJ), where 1 kJ equals 1000 J.
- Food energy is measured in kilocalories (kcal); 1 kcal is equivalent to 4.2 kJ.
Types of Energy
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Kinetic Energy: Energy of movement; associated with moving objects that produce heat. Calculated as:
- ( \text{Kinetic Energy} = \frac{1}{2} \times \text{mass (kg)} \times \text{speed}^2 )
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Potential Energy: Stored energy; found in objects capable of doing work. Gravitational potential energy formula:
- ( \text{Gravitational Potential Energy} = \text{mass (kg)} \times \text{gravitational field strength (9.8 m/s²)} \times \text{height (m)} )
Energy Transfer and Transformation
- Energy can be transferred (moving from one entity to another) or transformed (changing types of energy).
- Energy flow can be represented through diagrams, illustrating forms of energy and their transitions.
Energy Efficiency
- Efficiency refers to utilizing less energy to achieve work.
- Input energy: Energy put into a system (e.g., chemical potential energy from petrol).
- Output energy: Energy produced from the system (e.g., kinetic energy of a moving car).
- Unwanted energy forms, like heat and sound, are considered waste.
- Efficiency formula:
- ( \text{Efficiency} = \left( \frac{\text{Useful Output Energy}}{\text{Total Energy}} \right) \times 100 )
- Values must be in Joules or kilojoules, with results expressed as a percentage.
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Description
Explore the fundamental concept of energy with these test notes. Understand the various forms of energy and how it is measured in Joules. Learn through everyday examples of energy in action.