In this topic we are learning to: z Explain what energy is. z Illustrate ways that energy can be stored. z State the law of conservation of energy.
What Can Energy Do?
Energy makes many things possible. For example, energy allows a stereo to play music, rain to fall from the sky, a light bulb to glow and a computer to process information.
In all of these cases the common factor is that work is done. In physics, work is done when a force moves an object.
Energy is the ability to do work. The SI unit for energy is the joule (J).
What else does energy do?
Energy Fig. 16.1.1
Energy makes many things possible
How big is a joule?
To get an idea of how big a joule is, here are some everyday examples: z A joule is the amount of energy needed to raise the temperature of 1,000 cm3 of cool air by 1 °C. z A joule is the amount of energy needed to raise a small apple one metre off the ground. z As you read this book, you transform approximately 100 J of heat energy every second.
Using these figures, carry out the following tasks:
1. Calculate the amount of energy needed to raise the temperature of the air in the school laboratory by 1 °C.
2. Calculate how much heat energy is generated by all the people in your class in five minutes while they are sitting down doing a test.
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Fill in the blanks. Energy allows: A car to _____________. A fire to ____________. A person to _________.
A _________________ to ____________________?
16.1
Key Words Work
Thermal Chemical Light Sound Kinetic Potential Nuclear Magnetic Electrical
