The Magic Plank
Levers — a rod, a pivot, and suddenly you're strong
What this lesson covers
Why it matters
With a long rod and a small stone to rest it on, a child can lift a boulder. The rod doesn't care who pushes — it only cares WHERE.
Predict first
To lift a heavy rock most easily with a crowbar, hold it…
The farther from the pivot you push, the more turning power each newton buys. Distance is free strength.
- at the far end — as far from the pivot as possible — correct
- right next to the rock
- anywhere — it's the same
What you do
Set the arms of the crowbar so a 600 N rock gives in to a 200 N push.
Check yourself
Every lever has a fixed turning point called the…
Fulcrum (pivot), load (the job), effort (your push) — the three parts of every lever.
A see-saw balances a small child against a big one when the big one sits…
Weight × distance is what balances — the heavier side gives up distance.
Levers come in three orders, by what sits in the MIDDLE. A wheelbarrow (load in the middle) is…
Order 1: fulcrum in the middle (see-saw, scissors). Order 2: load in the middle (wheelbarrow, nutcracker). Order 3: effort in the middle (tongs, fishing rod).
- fulcrum — correct
- handle
- load
- closer to the middle — correct
- farther out
- on the ground
- a second-order lever — correct
- a first-order lever — like a see-saw
- not a lever at all