Javelin

Aim and method:

Unlike other throwing events, the athlete is allowed to sprint 30m to a throwing line before hurling the javelin.
The tip of the metal head must hit the ground first for the throw to be valid.

Equipment:

Early javelins were spears made of wood, with a sharpened end or an attached metal point. They often broke.

In the 1950s, a streamlined aluminium javelin was designed, enabling greater distances to be thrown. By the early 1980s, the aerodynamics had improved and the centre of gravity had to be modified to reduce distance!

Javelins have three parts: a head, a shaft and a cord grip at the javelinsÂ’ centre of gravity. (Place a ruler across your finger and where it balances is its centre of gravity. The shaft is smooth and often made of metal. The head is usually steel and tapers to a sharp point. The javelin must weigh at least 800 grams for men and 600g for women, and be 260 cm long for men and 220 cm for women. It must also be of specified width at certain points along its length.

For all throwing events, instead of a time-consuming and inaccurate tape measure, an Electronic Distance Measurement EDM) measures the distance from the throwing point to the impact point (of the javelin, for example) using an infra-red beam and reflector respectively.

It calculates the distance travelled using angle measurements, is accurate to within 1 mm, and the result is ready within about 10 seconds.
In shot put, discus and hammer throw, the object must be thrown from within a circle with a diameter of 2.5m for discus and 2.135m for shot put and hammer throw. The ring of the circle is iron, steel or other suitable material and set flush with the ground with concrete or another material filling the centre.
NSIC

In discus and hammer throw, this circle is partly surrounded by a cage for the safety of officials, competitors and spectators. The netting of this enclosure can be made of natural or synthetic fibre cord, or steel wire, provided it can stop a 2 kg discus moving at speeds up to 25 metres/sec, or a 7.26 kg hammer head moving at speeds up to 32 metres/sec, and prevent ricocheting.