Question

What is power? How do you differentiate kilowatt from kilowatt-hour? The Jog Falls in Karnataka state are nearly 20 m high. 2000 tonnes of waterfalls from it in a minute. Calculate the equivalent power if all this energy can be utilized? (g = 10 m s^–2)

Answer 1

Power is defined as the rate of doing work or the rate of transfer of energy, Kilowatt is the unit of power and kilowatt-hour is the unit of energy or work as a kilowatt-hour

= unit of power × unit of time.

Energy possessed by 2000 tonnes

(= 2000 x 10³ kg) water at a height of 20 m, Ef, = mgh

= 2000 x 10³ x 10 x 20

= 4 x 10⁸ J

Power generated if all this energy can be

utilized,

P = `"E"_"p"/"t"`

= `(4 xx 10^8 "J")/(60"s")` (∵ t = 1 min = 60 s)

= `2/3 xx 10^7  "W"`