Veda · OUT OF PURE CURIOSITY
How does a pulley help lift a load?
One fixed pulley · A moving pulley · Compare rope travel
One fixed pulley
A fixed pulley changes force direction. Pull down to lift the load up; ideally the force still equals the load’s weight.
A moving pulley
Two rope sections support the moving pulley. In this ideal model each supports half the weight, so less force is needed.
Compare rope travel
To lift the load one unit, pull two units of rope. Less force comes with a longer pulling distance.
For adults · discuss together
Rope and pulleys are weightless and frictionless. Total work does not decrease.
Before experience
Ask: “What do you think will happen?” Let the child check his guess first.
After the experience
What has changed? What remains the same? Where can you notice a similar phenomenon?
