Seesaw

From Free net encyclopedia

For other uses, see Seesaw (disambiguation).

Image:Up and down.jpg Image:Seesaw-aa.jpg Image:SeesawCorp1057.jpg

A seesaw (also known as a teeter-totter) is a long, narrow board suspended in the middle so that, as one end goes up, the other goes down.

In a playground setting, the board is balanced in the exact center. A person sits on each end and they take turns pushing their feet against the ground to lift their end into the air. Playground seesaws usually have handles for the riders to grip as they sit facing each other. One problem with the seesaw's design is that if a heavier child allows herself to hit the ground suddenly after jumping, or exits the seesaw at the bottom, the lighter child may fall and be injured. For this reason, seesaws are often mounted above a soft surface such as foam or wood chips.

In dog agility, the board is off balance so that the same end always returns to the ground after the dog has run across it.

Seesaws are also used in acrobatics.

Seesaws, and the eagerness of children to play with them, are also used to aid in mechanical processes. For example, at the Gaviotas community in Colombia, a children's seesaw is connected to a water pump.

For the mechanics of a seesaw see lever. The simple mechanics of a seesaw mean that they appear frequently in school exam paper questions.nl:wipwap ja:シーソー