wunder beta⚡ Energy & Work
What energy really is, its many forms, and why it is never lost.
What you’ll learn
- Define energy and identify its major forms, including kinetic and potential energy.Energy is the capacity to do work. It exists in many forms, including kinetic energy of motion and potential energy of position, which can convert into one another.
- Explain work, power, and efficiency and how work transfers energy.Work is a force acting over a distance, transferring energy; power is how fast work is done; and real machines are never fully efficient because of friction losses.
- Apply the law of conservation of energy to real transformations.Energy cannot be created or destroyed, only transformed. Roller coasters, pendulums, and friction all show energy changing form while the total stays constant.
Questions this course answers
How is energy best defined?
Energy is the capacity to do work or cause change, measured in joules, and it drives every event in the universe.
What determines an object's kinetic energy?
Kinetic energy depends on mass and speed, growing with the square of velocity, so faster objects carry much more.
A ball held high above the ground has which type of energy?
Because of its raised position, the ball stores gravitational potential energy that gravity can release as it falls.
In physics, when is work done on an object?
Work is done only when a force causes displacement; pushing on an unmoving wall does no physical work.
What does power measure?
Power is work done divided by time, measured in watts, describing how quickly energy is transferred.
Why is no machine 100 percent efficient?
Friction and other losses convert some input energy into unwanted heat, so useful output is always less than input.
Grounded in trusted sources
- Encyclopaedia Britannica, "Conservation of energy" (britannica.com)
- OpenStax Physics, "Mechanical Energy and Conservation of Energy" (openstax.org)
- The Feynman Lectures on Physics, Vol. I, Richard Feynman (1963)
- Physics LibreTexts, "Potential Energy and Conservation of Energy" (phys.libretexts.org)
Every Wunder lesson is built from real, reputable sources — never invented.
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