Levers & Simple Machines: The Physics of Mechanical Advantage
Small force. Big result. That is leverage.
Small force. Big result. That is leverage.
A lever is a rigid bar that pivots on a fulcrum. Push down on one side and the other side lifts. Adjust the fulcrum position and load weight to see how mechanical advantage works.
Levers come in three arrangements depending on where the fulcrum, effort, and load are positioned. Click each class to see examples.
Fulcrum in middle. Seesaw, crowbar, scissors.
Load in middle. Wheelbarrow, nutcracker, door.
Effort in middle. Tweezers, fishing rod, arm.
Every complex machine ever built, from bicycles to skyscrapers, is a combination of six simple machines. Click each one to see how it works.
Once you know the six simple machines, you see them everywhere.
Wheel and axle (wheels), lever (brake handles), pulley (chain on gears), inclined plane (gear teeth). Four simple machines in one vehicle.
Two Class 1 levers joined at a fulcrum, with wedge-shaped blades. The longer the handles relative to the blades, the more cutting force.
Lever (boom arm), pulley (cable system), wheel and axle (winch). A crane lifts 100-ton loads using the same principles you just explored.
The ancient Egyptians built the pyramids using only simple machines: inclined planes (ramps), levers (to position blocks), and possibly pulleys. No engines, no electricity. Just mechanical advantage and human effort.
You've discovered how levers multiply force, how fulcrum position changes everything, and how the six simple machines underlie every complex device from bicycles to cranes.
A lever trades distance for force. Push a longer distance on one side and the other side pushes harder over a shorter distance. Energy is conserved.
Move the fulcrum closer to the load and you need less force. The trade-off: you must push your side farther. Mechanical advantage = effort arm / load arm.
Class 1: fulcrum in middle (seesaw). Class 2: load in middle (wheelbarrow). Class 3: effort in middle (tweezers). Same physics, different arrangements.
Every complex machine is a combination of six simple machines: lever, wheel/axle, pulley, inclined plane, wedge, and screw.
Put your new knowledge into practice!