Define watt. Express kilowatt in terms of joule per second. A 200 kg car engine develops 500 W for each kg. What force does it exert in moving the car at a speed of 20 m s–1?
One watt is the power of work done per unit time.
1 P = 1 J / 1 s .
1 kilowatt = 1000 J s–1
For 1 Kg power developed = 500W
Total Power for 200 kg = 200 × 500 = 1 × 104 W
Velocity of the car = 20m/s