Levers
A rigid bar pivoting on a fulcrum (pivot point). Three classes based on fulcrum position:
| Class | Fulcrum position | Examples | MA |
|---|---|---|---|
| I | Between effort and load | Seesaw, crowbar, scissors | Can be > 1, = 1, or < 1 |
| II | Load between fulcrum and effort | Wheelbarrow, nutcracker, bottle opener | Always > 1 |
| III | Effort between fulcrum and load | Tweezers, fishing rod, human forearm | Always < 1 (gain speed) |
MA = effort arm length / load arm length
Example: Effort arm 3 m, load arm 1 m → MA = 3. Apply 100 N → lifts 300 N.