Q27Long answer
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 m s–1?
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One watt is the power of an agent which does work at the rate of 1J s–1 1 kilowatt = 1000 J s–1 Total Power = 150 × 500 = 7.5 × 104 W Power 7.5 ×104 Force = = = 3.75 ×10 3 N velocity 20 Force = 3750 N.