Ok, it’s a little more than just ‘how to throw far’, but knowing the physics of how objects fly through the air can help field-eventers, write Jamie French and Matt Long
In athletics events “projectile motion” is applied when an object – namely a shot, hammer, discus, javelin, or even a body in the jumps, is projected by external force which then continues in motion by its own inertia.
The complicated formula that underpins projectile theory can be translated into a number of fundamental principles that provide the key technical development of both throws and jumps.
Four main controllable factors influence how far a body (throwing implement or actual body) will travel through the air, each of which can have a significant impact on achieving distance travelled.
Funnily enough, this refers to the speed of the object at the point at which it is released or leaves the ground and, all other factors being equal, has the biggest effect on how far something will travel.
Put simply, the faster the implement is moving at the time of release, the further it will go. However, although this may be the case, the application of correct technique or changing a body’s direction of travel, becomes more difficult as more speed is applied.
So while jumpers and throwers may try to increase the speed of take-off or release, this can only be done to a level that the athlete can use. This then changes from a maximum speed of release or take-off, to an “optimal”, or in other words, the maximum speed that can be usefully controlled.
The angle of release or take-off is a result of the relative proportions of speed in two directions: vertical and horizontal. Theoretically, in the absence of any other influences, if these figures are equal then the angle of release or take-off will be 45 degrees and is the optimum angle for any object in flight that takes off or is released from the same level that it lands.
However, if the vertical speed is increased proportionally to the horizontal speed, the angle achieved will increase. Conversely, if the horizontal speed is greater than the vertical speed, the angle will decrease. Although this may be true for objects with a uniform shape, released or taking-off from the same level that they will land, the optimum angles will change if the shape alters, especially so if the height of release is also changed.
This is the distance from the floor that an object or body is released or takes-off from relative to the landing. Increases in height of release or take-off serve to provide more time that the object will stay in the air, which subsequently increases the amount of distance achieved. For objects with a uniform shape (such as a shot) the additional distance achieved is largely proportional to the increases in height from the floor.
The increases in height are difficult to achieve in competition, only being achieved by alterations in technique and tend to only have relatively small effects. However, for some objects, this change may affect aerodynamic properties that could mean the increase in distance changes.
Aerodynamics works on the principles that the air around us has substance and therefore an object travelling through the air, either on the run-up or in-flight, will behave differently depending upon its shape and how it travels. Objects with a uniform shape (same all the way around irrespective of viewing angle) such as a shot, experience no noticeable changes in aerodynamic properties. However, objects with different shapes will have differences in sizes of surfaces exposed to the resistance that the air provides as a result of its substance and will experience varying amounts of drag or lift.
Therefore, the angle of attack or incidence, or way that the implement travels through the air, will need to differ to optimise these aerodynamic effects.
» Jamie French is a UKA regional trainer and Dr Matt Long a UKA coach education tutor. The assistance of Trevor Hopkins and Neil Wheeler of UKA is acknowledged