The definition of work says nothing about the time during which the work is done. A porter does the same amount of work in carrying a load up a flight of stairs whether he runs up or walks up. But he feels more tired when he runs up. To distinguish between such cases, the concept of power is introduced. Power is defined as the rate of doing work.
Power = work done / time taken
Thus, when the porter runs up he develops more power and therefore, gets tired. A strong boy can climb a hill in less time than a weak boy of the same weight because the former is capable of developing more power. The unit of power is watt (W).
Power = work done / time taken
Thus, when the porter runs up he develops more power and therefore, gets tired. A strong boy can climb a hill in less time than a weak boy of the same weight because the former is capable of developing more power. The unit of power is watt (W).
