Health

Give your family the gift of regular exercise

(HealthDay)—Physical activity could be the best gift to give your family this holiday season. And the American Heart Association (AHA) has some suggestions on how to do that.

Alzheimer's disease & dementia

Football and dementia: heading must be banned until the age of 18

Alarm bells are ringing in sport about the risk of a group of chronic, neuro-degenerative diseases, commonly understood as dementia. There is an increasingly large body of evidence which has identified that small, repetitive ...

Pediatrics

Getting kids moving and learning

Children are set to move more, improve their skills, and come up with their own creative tennis games with the launch of 'HomeCourtTennis', a new initiative to assist teachers and coaches with keeping kids active while at ...

Neuroscience

Babies retain even detailed events during a nap

The brain is permanently exposed to new impressions. Even when sleeping, it does not rest and processes recent experiences. In very early childhood, it has been thought that sleep primarily promotes semantic memory. This ...

page 1 from 6

Ball

A ball is a round, usually spherical but sometimes ovoid, object with various uses. It is used in ball games, where the play of the game follows the state of the ball as it is hit, kicked or thrown by players. Balls can also be used for simpler activities, such as catch, marbles and juggling. Balls made from hard-wearing materials are used in engineering applications to provide very low friction bearings, known as ball bearings. Black powder weapons use stone and metal balls as projectiles.

Although many types of balls are today made from rubber, this form was unknown outside the Americas until after the voyages of Columbus. The Spanish were the first Europeans to see bouncing rubber balls (albeit solid and not inflated) which were employed most notably in the Mesoamerican ballgame. Balls used in various sports in other parts of the world prior to Columbus were made from other materials such as animal bladders or skins, stuffed with various materials.

As balls are one of the most familiar spherical objects to humans, the word "ball" is used to refer to, or to describe, anything spherical or near-spherical.

This text uses material from Wikipedia, licensed under CC BY-SA