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PFY P 120

 

F) power is the rate of doing work

Power (in watts) = work done (in watts) / time (in seconds)

G) 1 watt is a rate of working of one joule per second

13) a girl does 1000 joules of work in 5 seconds. What power does she develop? 1000/5= 5000W

14) a man lifts a weight of 300N through a vertical height of 2m in 6 seconds. What power does he develop? 300 x 2 = 600W

16) a crane lifts a load of 3000N through a vertical height of 10m in 4 seconds. What is its rate of working  in a) watts b) kilowatts  

a) 3000 x 10 = 30,000W

b) 30kW