Pulling power
Inventors (Intermediate), mission I7 Pulleys & Belts, lesson 3 of 6.
Hook
Can pulleys make you twice as strong? Three times?
Fair test
Force needed vs number of supporting strings (1, 2, 3). Graph force and rope pulled.
Bonus challenge
Lift a teacher-sized load (a full backpack) with the best setup.
The build
Pulley Hoist: A tower with a crank winch and a block-and-tackle. One pulley, then two: the spring scale shows the pull halving.