the SI unit of work or energy, equal to the work done by a force of one newton when its point of application moves one metre in the direction of action of the force
(seconds, s) the indefinite continued progress of existence and events that occur in apparently irreversible succession from the past through the present to the future.
The percentage of the input work that is converted to output work. = useful output energy supplied by device (J) / total input energy of the device (J) x 100