Mechanical Work, Power and Energy; Conservation
Why lifting a heavy bag tires you out, and where that effort goes
Big Idea: When a force pushes or pulls a body and the body actually moves, the force does work. Doing work transfers energy from one body to another or changes it from one kind into another. Energy is never lost — it only moves around or changes form. This single idea explains falling stones, swinging pendulums and the electricity from a mountain river.
By the end you will be able to:
- calculate mechanical work with A = F · s,
- say when a force does zero work,
- find power with N = A / t and use watts,
- describe kinetic energy (Ek = mv2/2) and potential energy (Ep = mgh),
- explain how one kind of energy turns into the other,
- state the law of conservation of mechanical energy.