Block and tackles

HOW

1. Note how the pull-up mechanism for each of the three seats looks.
2. Sit on one of them and pull the rope.
3. Pay attention to the effort you have to put into pulling the rope.
4. Compare the effect on other seats.

WHY

The seat-lift mechanism is a system of pulleys (block and tackles) belonging to what is known as simple machines. Their tasks are to change the direction of the force (you move upwards, although you pull the rope downwards) and to reduce it. The value of the weight reduction depends on the number of pulleys and how they are connected.