Beach ball
Encyclopedia
A beach ball is an inflatable ball for beach
Beach
A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...

 and water games. Their large size ball and light weight take little effort to propel; they travel very slowly and generally must be caught with two hands, making them ideal for lazy games and for children. Their lightness and size make them difficult to use in even moderate wind.

The beach ball's invention is usually credited to Jonathon DeLonge in 1938.

Design

Beach balls range from hand-sized to over 3 feet (1 m) across or bigger. They generally have a set of soft plastic panels, with two circular end panels, one with an oral inflation valve
Oral inflation valve
An oral inflation valve is present on most swim toys and beach balls. Since the valve is placed in the mouth and saliva can be ejected into the inflatable object, the valve is subjected to some health concerns....

, intended to be inflated by mouth or pump. A common design is vertical solid colored stripes alternating with white stripes. Some are printed with advertisements or company slogans, or painted as globes.

Uses

Beach ball sports include water polo
Water polo
Water polo is a team water sport. The playing team consists of six field players and one goalkeeper. The winner of the game is the team that scores more goals. Game play involves swimming, treading water , players passing the ball while being defended by opponents, and scoring by throwing into a...

 and volleyball
Volleyball
Volleyball is a team sport in which two teams of six players are separated by a net. Each team tries to score points by grounding a ball on the other team's court under organized rules.The complete rules are extensive...

. While they are much less expensive than the balls used in professional sports, they are also much less durable as they are made of soft plastic. Giant beach balls may be hit around between crowd members at rock
Rock music
Rock music is a genre of popular music that developed during and after the 1960s, particularly in the United Kingdom and the United States. It has its roots in 1940s and 1950s rock and roll, itself heavily influenced by rhythm and blues and country music...

 concerts and sporting events. Many graduates use beach balls as a prank during ceremonies, hitting them around the crowd. Their light weight and stability made them ideal for trained seals balancing a beach ball on their noses. They are a popular prop in swimsuit photography.

Bernoulli beach ball demonstration

The Bernoulli beach ball demonstration is a way of demonstrating Bernoulli's principle
Bernoulli's principle
In fluid dynamics, Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy...

, that for an inviscid flow
Inviscid flow
In fluid dynamics there are problems that are easily solved by using the simplifying assumption of an ideal fluid that has no viscosity. The flow of a fluid that is assumed to have no viscosity is called inviscid flow....

, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

 or a decrease in the fluid
Fluid
In physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....

's potential energy
Potential energy
In physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. The SI unit of measure for energy and work is the Joule...

. The demonstration uses an air blower to suspend a beach ball in the air. The ball is locked in position because of the low pressure of the moving air around the ball. When the ball moves away, the higher pressure of the still air forces it back in.
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