Finally, when one picks up a calculus book, you are moving the book against the force due to the acceleration due to gravity. Hence work is done. {{CMD_78}} {{CMD_79}} We can write the definition of work in the language of calculus as, {{MATH_80}} The SI unit of work is also a {{CMD_81}}. To help understand this, {{MATH_82}} joule is approximately how much work is done when you raise an apple one meter.