When you pull the opposite end of the rope, the pulley mechanism changes the direction of the force applied, which lifts a load like this. The more pulley wheels you add to the mechanism ...

Weigh the 1-kg mass using the scale. Put a 1-kg mass on the 1:1 pulley. Use the scale to measure the force required to lift the 1-kg mass. Repeat for the other pulleys. If you have any questions about ...