Mystery #4Tier 3simple machines / pulleys

How does a rope looped through pulleys let one person lift a very heavy load?

One person, on their own, hauls a piano up to a high window using nothing but a rope threaded through a set of little wheels. Lifted straight up, that piano would flatten them. Yet with the rope looped back and forth, they pull it up steadily by hand. How does a bit of rope turn one person into a giant?

A block and tackle against a blue sky, with rope wound several times between an upper and a lower set of pulley wheels — Photo: Ludovic Péron · CC BY-SA 3.0 · via Wikimedia Commons

Your guess

The rope is clearly doing something clever. What do you think it is?

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