The slide is an example of the simple machine known as the inclined plane,[1][circular reference] which makes moving objects up and down easier, or in this case more fun.
The slide may be flat, or half cylindrical or tubular to prevent falls.
They have a smooth surface called a 'slide bed' that is either straight for the full length or can contain bends.
[11][12] Indeed, Arthur Leyland's book "Playground Technique and Playcraft", volume 1, originally published in 1909 and revised in 1913, gives full instructions for the construction of a metal playground slide.
The most obvious is that when a slide is not enclosed and is elevated above the playground surface, then users may fall off and incur bumps, bruises, sprains, broken bones, or traumatic head injuries.