Now that we understand some of the different types of energy, let's learn about what makes energy so special: the conservation of energy.
The total sum of the energy in the universe today is the same amount as it was yesterday, and last week, and billions of years ago. The total amount of energy never changes over time, but the amounts of each type of energy can change as energy is converted between different forms. The lecture in the link below from physicist Richard Feynman gives a great summary of how we can think about the conservation of energy:
After we understand isolated systems and the conservation of energy, we can learn how energy is transferred into or out of a non-isolated system through work.
Work is another word that people use a lot but has a very specific meaning in physics: the transfer of energy into or out of a system due to a force which causes a displacement. We can calculate work as the force applied to an object multiplied by the displacement of the object. If you push someone on a sled and increase their speed, you've done work on that person and increased their kinetic energy. If you lift up a box, you've done work on the box and increased its gravitational potential energy.
One more common word that has a specific physics definition is power: a change in energy (or work) per unit of time. If you increased the speed of the sled or the height of the box in less time then you would have exerted more power. You might be more familiar with electrical power, but we're only going to cover mechanical power in this course.
- Conservation of Energy
- Work
- Power
Now that we understand some of the different types of energy, let's learn about what makes energy so special: the conservation of energy.
The total sum of the energy in the universe today is the same amount as it was yesterday, and last week, and billions of years ago. The total amount of energy never changes over time, but the amounts of each type of energy can change as energy is converted between different forms. The lecture in the link below from physicist Richard Feynman gives a great summary of how we can think about the conservation of energy:
After we understand isolated systems and the conservation of energy, we can learn how energy is transferred into or out of a non-isolated system through work.
Work is another word that people use a lot but has a very specific meaning in physics: the transfer of energy into or out of a system due to a force which causes a displacement. We can calculate work as the force applied to an object multiplied by the displacement of the object. If you push someone on a sled and increase their speed, you've done work on that person and increased their kinetic energy. If you lift up a box, you've done work on the box and increased its gravitational potential energy.
One more common word that has a specific physics definition is power: a change in energy (or work) per unit of time. If you increased the speed of the sled or the height of the box in less time then you would have exerted more power. You might be more familiar with electrical power, but we're only going to cover mechanical power in this course.
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