Picture Description:
The picture provided showcases a see-saw or a teeter-totter. It consists of a long, narrow board balanced on a fulcrum in the center.

Combination of Simple Machines:
The see-saw is a combination of two simple machines: the lever and the fulcrum.

The Lever:
The lever is a simple machine that consists of a rigid bar or board that rotates on a fixed point called the fulcrum. In the case of the see-saw, the long board acts as the lever.

The Fulcrum:
The fulcrum is the point on which the lever rotates or pivots. In the see-saw, the fulcrum is located at the center of the board, allowing it to tilt up and down.

How it Works:
When two people sit on opposite ends of the see-saw, their weights create a force that causes the see-saw to tilt. This force can be balanced by adjusting the positions of the individuals on the see-saw.

Demonstrating the Lever Principle:
The see-saw demonstrates the lever principle, which states that a small force applied over a long distance can balance a larger force applied over a shorter distance. When one person pushes down on their end of the see-saw, their weight creates a force that is transferred through the lever to the other end. This force causes the other person to rise up.

Equilibrium:
The see-saw will achieve a state of equilibrium when the forces on both ends are balanced. This occurs when the distance of the heavier person from the fulcrum is shorter and the distance of the lighter person from the fulcrum is longer.

Applications in Real Life:
See-saws are commonly found in playgrounds and parks, providing children with an enjoyable way to experience the principles of balance and simple machines. They also serve as a great example for understanding the concept of force, weight, and equilibrium.

In conclusion, the see-saw is a combination of the lever and the fulcrum. It demonstrates the lever principle and provides an interactive experience for children to understand the concepts of balance and simple machines.