Overview
This lecture explains the concept of levers as simple machines, describes their three classes, and introduces a mnemonic device to remember them.
What Are Levers?
- Levers are simple machines found in tools and the human body.
- A lever works by applying force at one point to move a load at another point, pivoting around a fulcrum.
- The arrangement of the force, load, and fulcrum determines the lever class.
Classes of Levers
- First class lever: Fulcrum is between the force and load (e.g., seesaw, scissors, pliers).
- Second class lever: Load is between the force and fulcrum (e.g., wheelbarrow, nutcracker, stapler).
- Third class lever: Force (effort) is between the fulcrum and load (e.g., hockey stick, rake, hammer).
Mnemonic Device: FLE 1-2-3
- Write "FLE" with numbers 1, 2, 3 below to remember lever classes.
- "F" stands for fulcrum, "L" for load, "E" for effort (force).
- First class: "F" under 1; fulcrum in the middle.
- Second class: "L" under 2; load in the middle.
- Third class: "E" under 3; effort in the middle.
Key Terms & Definitions
- Lever — A simple machine with a rigid bar that pivots around a fulcrum to move a load.
- Fulcrum — The pivot point of a lever.
- Load — The object to be moved by the lever.
- Effort/Force — The input force applied to the lever.
Action Items / Next Steps
- Review the FLE 1-2-3 mnemonic for memorizing lever classes.
- Study examples of each lever class and identify them in real life.