Editing Hammer (section)

===Effect of gravity===
[[Gravity]] exerts a force on the hammer head. If hammering downwards, gravity increases the [[acceleration]] during the hammer stroke and increases the [[energy]] delivered with each blow. If hammering upwards, gravity reduces the acceleration during the hammer stroke and therefore reduces the energy delivered with each blow. Some hammering methods, such as traditional mechanical [[pile driver]]s, rely entirely on gravity for acceleration on the down stroke.