A mechanism that dissipates energy during a fall or limits energy during fall arrest, like air resistance in a parachute, is essential for safety. Dissipative forces reduce system energy, while driving mechanisms, like in a pendulum clock, compensate for energy lost to friction.
The mechanism used to dissipate energy during a fall or limit the energy imposed on an employee during a fall arrest is crucial in safety engineering. When an object falls, gravitational force acts upon it, and if a person were involved in a fall, the energy of the fall needs to be managed to prevent injury. This management of energy is where dissipative forces come into play.
Dissipative forces, such as air resistance or friction, work against the gravitational pull and do negative work, which translates to a reduction of kinetic and potential energy of the falling object or person, as described by the energy dissipation equation Ediss = Wnc,if| = |Δ(K + U)if|. For instance, as a skydiver falls, before opening the parachute, there is a transformation between kinetic and potential energy, where potential energy is converted into kinetic energy.
To prevent a hazardous impact, a fall-arrest system, like a parachute, increases air resistance drastically, thereby increasing the dissipative forces to reduce the skydiver's speed.
In a system like a pendulum clock, damping forces such as air resistance and friction at the pivot point can reduce the amplitude of the pendulum's oscillations. However, the clock has a driving mechanism, typically a weight or a spring, which compensates for the energy loss to ensure that the pendulum continues to swing at a consistent amplitude and keeps accurate time.
So, these mechanisms, by either dissipating or compensating for energy, serve to either protect workers in the case of fall-arrest systems or maintain the function of machines like pendulum clocks.