Glossary Dyne: the force required to accelerate 1 g of mass at 1 cm per second; 1 dyne = 10- 5 newtons Energy: the ability or capacity to do work; in physics, essentially synonymous with work Energy density: energy per unit area; in lasers, units = joules/cm2 Erg: a dyne-centimeter; the work or energy of 1 dyne applied over a distance of 1 cm; a unit of energy; 1 erg = 10- 7 joules Joule: a newton-meter; the work or energy of 1 newton applied over a distance of 1 meter; a unit of energy; 1 joule = 107 ergs Nanosecond: a billionth (10- 9) of a second Newton: the force needed to accelerate 1 kg of mass at 1 meter per second per second; 1 newton = 105 dynes Picosecond: a trillionth (10- 12) of a second Power: energy per unit of time; how fast energy is produced or transferred Power density: power per unit area; in lasers, units = watts/cm2 Watt: one joule per second; a unit of power Work: “force times distance”; the product of a force and the distance through which it produces displacement; synonymous with energy