Hammering a Nail into a Board
A hammer from height with mass 1 kg provides a force to hit a 2 cm nail into a wooden block with resistance . (The hammer and nail are not drawn to scale.)
Work is defined as , where is the force (the weight of the hammer) and is the distance that an object moves; in this case, there are two relevant distances: the height of the hammer as it falls and the depth of the nail.
It's assumed that the wood is soft enough so that the nail completely penetrates the board; in real life, resistance is greater according to the type of wood, or whether the nail is driven perpendicularly to the grain of wood and other factors.
A fraction of the kinetic energy of the hammer is converted into heat and sound.