Define watt. Express kilowatt in terms of joule per second. A 150-kg car engine develops 500 W for each kg. What force does it exert in moving the car at a speed of 20 ms–1?
One watt is the power of an agent which does work at the rate of 1Js-1
1 kilowatt = 1000 Js-1
Total power = 150 � 500 = 7.5 � 104 W
